Answer:
The population proportion is 0.1057.
For samples of size n: Mean = 0.1057, Standard deviation [tex]s = \frac{0.3075}{\sqrt{n}}[/tex]
Step-by-step explanation:
Central Limit Theorem for Proportions:
For a proportion p in a sample of size n, the sampling distribution of the sample proportion will be approximately normal with mean [tex]\mu = p[/tex] and standard deviation [tex]s = \sqrt{\frac{p(1-p)}{n}}[/tex]
Population proportion:
Of 30,000 people, 3,170 people either drive a hybrid car or have indicated on a recent survey that they would be interested in driving one.
This means that [tex]p = \frac{3170}{30000} = 0.1057[/tex]
The population proportion is 0.1057.
Mean and standard deviation of the sampling distribution for samples of size n
By the Central Limit Theorem, the mean is [tex]\mu = p = 0.1057[/tex]
Standard deviation:
[tex]s = \sqrt{\frac{0.1057*0.8943}{n}} = \frac{0.3075}{\sqrt{n}}[/tex]
A bag contains 6 red balls and 9 black balls. Two balls are drawn, one after the other with replacement. Find the probability that
a. Both are of the same colours
b. Both are of different colours
Answer:
a) 13/25
b) 12/15
Step-by-step explanation:
a) Since it is with replacement, the chance of them being both the same colour will be
P(both red) + P(both black) = (6/15*6/15) + (9/15*9/15)
= 13/25
b) If they are both different colours, then we will be working out
P(both colours) = (6/15*9/15)*2 = 12/25 (Its *2 because the other way of pulling both colours is 9/15*6/15 which is the same but flipped)
Another way of working this question out is
P(1-All red or all blue) which from above we know that All red or all blue is 13/25 so
P(1-All red or all blue) = 1 - 13/25 = 12/25
A random sample of 4000 U.S. citizens yielded 2280 who are in favor of gun control legislation. Find the point estimate for estimating the proportion of all Americans who are in favor of gun control legislation.
Answer:
[tex] n= 4000[/tex] represent the sample size of citizens selected
[tex] X= 2280[/tex] represent the people who are in favor of gun control legislation
[tex]\hat p =\frac{X}{n}[/tex]
And replacing we got:
[tex]\hat p= \frac{2280}{4000}= 0.57[/tex]
Step-by-step explanation:
For this problem we have the following info given:
[tex] n= 4000[/tex] represent the sample size of citizens selected
[tex] X= 2280[/tex] represent the people who are in favor of gun control legislation
And for this case we want to estimate the roportion of all Americans who are in favor of gun control legislation and for this case we can use the following formula:
[tex]\hat p =\frac{X}{n}[/tex]
And replacing we got:
[tex]\hat p= \frac{2280}{4000}= 0.57[/tex]
The Downtown Parking Authority of Tampa, Florida, reported the following information for a sample of 228 customers on the number of hours cars are parked and the amount they are charged.
Number of Hours Frequency Amount Charged
1 21 $4
2 36 6
3 53 9
4 40 13
5 22 14
6 11 16
7 9 18
8 36 22
228
A. Convert the information on the number of hours parked to a probability distribution. Is this a discrete or a continuous probability distribution?
B. Find the mean and the standard deviation of the number of hours parked. How would you answer the question: How long is a typical customer parked?
C. Find the mean and the standard deviation of the amount charged.
Answer: A. This is a discrete probability distribution.
hours probability
1 0.09
2 0.16
3 0.23
4 0.17
5 0.09
6 0.05
7 0.04
8 0.16
B. E(X) = 4.12; σ = 2.21
C. μ = 12.75; s = 6.11
Step-by-step explanation: Probability Distribution is an equation or table linking each outcome of an experiment with its probability of ocurrence. For this case, since the experiment is performed a high number of times and in a long run, the relative frequency of the event is its probability. Therefore:
A. To convert to a probability distribution, find the probability through the frequency by doing:
Hour 1
P(X) = [tex]\frac{21}{228}[/tex] = 0.09
Hour 2
P(X) = [tex]\frac{36}{228}[/tex] = 0.16
Hour 3
P(X) = [tex]\frac{53}{228}[/tex] = 0.23
Hour 4
P(X) = [tex]\frac{40}{228}[/tex] = 0.17
Hour 5
P(X) = [tex]\frac{22}{228}[/tex] = 0.09
Hour 6
P(X) = [tex]\frac{11}{228}[/tex] = 0.05
Hour 7
P(X) = [tex]\frac{9}{228}[/tex] = 0.04
Hour 8
P(X) = [tex]\frac{36}{228}[/tex] = 0.16
The table will be:
hours probability
1 0.09
2 0.16
3 0.23
4 0.17
5 0.09
6 0.05
7 0.04
8 0.16
This is a discrete distribution because it lists all the possible values that the discrete variable can be and its associated probabilities.
B. Mean for a probability distribution is calculated as:
E(X) = ∑[[tex]x_{i}[/tex].P([tex]x_{i}[/tex])]
E(X) = 1*0.09 + 2*0.16+3*0.23+4*0.17+5*0.09+6*0.05+7*0.04+8*0.16
E(X) = 4.12
Standard Deviation is:
σ = √∑{[x - E(x)]² . P(x)}
σ = [tex]\sqrt{(1-4.12)^{2}*0.09 + (2-4.12)^{2}*0.16 + ... + (7-4.12)^{2}*0.04 + (8-4.12)^{2}*0.16}[/tex]
σ = [tex]\sqrt{4.87}[/tex]
σ = 2.21
The average number of hours parked is approximately 4h with a standard deviation of approximately 2 hours, which means that a typical costumer parks between 2 to 6 hours.
C. Mean for a sample is given by: μ = ∑[tex]\frac{x_{i}}{n}[/tex] , which is this case is:
μ = [tex]\frac{4+6+9+13+14+16+18+22}{8}[/tex]
μ = 12.75
Standard Deviation of a sample: s = √[tex]\frac{1}{n-1}[/tex]∑([tex]x_{i}[/tex] - μ)²
s = [tex]\sqrt{ \frac{(4-12.75)^{2} + (6-12.74)^{2} + ... + (18-12.75)^{2} + (22-12.75)^{2} }{8-1}}[/tex]
s = 6.11
The average amount charged is 12.75±6.11.
It take Donna 15 minutes to complete 3 levels of Candy Crush. At this rate, how many levels will she complete in 3 hours?
Answer: she will have 36 levels completed
Find the value of x and the value of y.
A r= 15, y = 10/3
B. r=20, p=10/3
C. x=20/3, y = 513
D. r=15, y =53
Answer:
Step by step solution:
can 10/12 be simplified
Answer:
5/6
Step-by-step explanation:
10/12
Divide the top and bottom by 2
10/2 = 5
12/2 =6
the fraction becomes 5/6
Answer :
10/12
Reduce the fraction
= 5/6
Solve for b. -11b+7 = 40 Two step equations
Step-by-step explanation:
-11b + 7 = 40
-11b = 40 - 7
-11b = 33
b = 33/-11
b = - 3
Benny is trying to learn how to ride a bike, but is terrified of falling. He did some research, and discovered that if he rides a bike with training wheels, the probability of falling is 0.1; if he learns to ride a bike by using a bike without training wheels, his probability of falling is 0.5, and if he uses a unicycle, his probability of falling is 0.8. Benny came home crying with a bruise on his knee, after falling. His mom is trying to guess how Benny was trying to learn to ride a bike.
a) Assuming that the probability that Benny was using each of these 3 methods is equal, what is the probability that Benny was learning to ride a bike using the training wheels?
b) Since Benny's mom knows Benny so well, she knows that the probability that he was using training wheels is 0.7, regular bike is 0.2, and unicycle is 0.1. What is the probability now that Benny fell while using the training wheels?
Answer:
a) 7.14% probability that Benny was learning to ride a bike using the training wheels
b) 28% probability that Benny was learning to ride a bike using the training wheels
Step-by-step explanation:
Bayes Theorem:
Two events, A and B.
[tex]P(B|A) = \frac{P(B)*P(A|B)}{P(A)}[/tex]
In which P(B|A) is the probability of B happening when A has happened and P(A|B) is the probability of A happening when B has happened.
Benny came home crying with a bruise on his knee, after falling. His mom is trying to guess how Benny was trying to learn to ride a bike.
a) Assuming that the probability that Benny was using each of these 3 methods is equal, what is the probability that Benny was learning to ride a bike using the training wheels?
So
Event A: Benny fell
Event B: Benny was using training wheels.
The probability that Benny was using each of these 3 methods is equal
This means that [tex]P(B) = \frac{1}{3}[/tex]
He did some research, and discovered that if he rides a bike with training wheels, the probability of falling is 0.1;
This means that [tex]P(A|B) = 0.1[/tex]
Probability of falling:
1/3 of the time, he uses training wheels. With training wheels, the probability of falling is 0.1.
1/3 of the time, he uses the bike without training wheels. Without training wheels, the probability of falling is 0.5
1/3 of the time, he uses the unicycle, for which he has an 0.8 probability of falling. Then
[tex]P(A) = \frac{0.1 + 0.5 + 0.8}{3} = 0.4667[/tex]
So
[tex]P(B|A) = \frac{\frac{1}{3}*0.1}{0.4667} = 0.0714[/tex]
7.14% probability that Benny was learning to ride a bike using the training wheels
b) Since Benny's mom knows Benny so well, she knows that the probability that he was using training wheels is 0.7, regular bike is 0.2, and unicycle is 0.1. What is the probability now that Benny fell while using the training wheels?
Similar as above, just some probabilities change.
Event A: Benny fell
Event B: Benny was using training wheels.
The probability that he was using training wheels is 0.7
This means that [tex]P(B) = 0.7[/tex]
He did some research, and discovered that if he rides a bike with training wheels, the probability of falling is 0.1;
This means that [tex]P(A|B) = 0.1[/tex]
Probability of falling:
0.7 of the time, he uses training wheels. With training wheels, the probability of falling is 0.1.
0.2 of the time, he uses the bike without training wheels. Without training wheels, the probability of falling is 0.5
0.1 of the time, he uses the unicycle, for which he has an 0.8 probability of falling. Then
[tex]P(A) = 0.7*0.1 + 0.2*0.5 + 0.1*0.8 = 0.25[/tex]
So
[tex]P(B|A) = \frac{0.7*0.1}{0.25} = 0.28[/tex]
28% probability that Benny was learning to ride a bike using the training wheels
A model with 12 squares labeled exact value and 3 squares labeled error. A model with 18 squares labeled exact value and 3 squares labeled Error. Which is true of the models? Check all that apply. Both exact values are less than the approximate value. The percent errors are the same. The top model has a greater percent error. The bottom model has a greater percent error. The absolute error is the same for both.
Answer:
a,c,e
Step-by-step explanation:
on edge-
Answer:
The answer is A, C, E
Jalisa earned $71.25 today babysitting, which is $22.50 more than she earned babysitting yesterday. The equation d + 22.50 = 71.25 can be used to represent this situation, where d is the amount Jalisa earned babysitting yesterday. Which is an equivalent equation that can be used to find the amount Jalisa earned babysitting yesterday? 71.25 minus 22.50 = d 71.25 + 22.50 = d d + 71.25 = 22.50 d minus 22.50 = 71.25
Answer:
71.25 - 22.50 = d
Step-by-step explanation:
To find how much she earned yesterday, we subtract how much she earned today by the amount more she earned.
Answer:
A
Step-by-step explanation:
Need help with this . The picture is enclosed
Answer: (fоg)(24)=5
Step-by-step explanation:
(fоg)(24) is f of g of 24. This means you plug in g(24) into f(x).
[tex]g(24)=\sqrt{24-8}[/tex]
[tex]g(24)=\sqrt{16}[/tex]
[tex]g(24)=4[/tex]
Now that we know g(24), we can plug it into f(x).
f(4)=2(4)-3
f(4)=8-3
f(4)=5
Assume the random variable X has a binomial distribution with the given probability of obtaining a success. Find the following probability, given the number of trials and the probability of obtaining a success. Round your answer to four decimal places. P(X≤2), n=5, p=0.8
Answer:
0.0579
Step-by-step explanation:
P(X≤2) = P(X=0) + P(X=1) + P(X=2)
P(X≤2) = ₅C₀ (0.8)⁰ (0.2)⁵ + ₅C₁ (0.8)¹ (0.2)⁴ + ₅C₂ (0.8)² (0.2)³
P(X≤2) = 0.00032 + 0.0064 + 0.0512
P(X≤2) = 0.0579
Probability of obtaining a success is 0.0579 .
Here,
Binomial distribution formula:
P(x:n,p) = nCx px (1-p)n-x Or P(x:n,p) = nCx px (q)n-x
Substituting the values of n and p
n = 5
p = 0.8
So,
P(X≤2) = P(X=0) + P(X=1) + P(X=2)
P(X≤2) = ₅C₀ (0.8)⁰ (0.2)⁵ + ₅C₁ (0.8)¹ (0.2)⁴ + ₅C₂ (0.8)² (0.2)³
P(X≤2) = 0.00032 + 0.0064 + 0.0512
P(X≤2) = 0.0579
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4. Rational, irrational (4 points) (1) (2 points) Prove or disprove that if x y is an irrational number, then x or y is also an irrational number. (2) (2 points) Prove that if x 2 is irrational, then x is irrational. (Hint: try a proof by contrapositive)
Answer:
See explanation below
Step-by-step explanation:
1) Prove or disprove that if [tex] x^y[/tex] is an irrational number, then x or y is also an irrational number.
Let's take the following instances:
i) When x= 2 and y=[tex] \sqrt{2} [/tex] we have: [tex] 2^\sqrt^{^2^} [/tex]
ii) When [tex] x=2\sqrt{2} [/tex] and y=3, we have: [tex] (x=2\sqrt{2})^3 [/tex]
iii) When [tex] x=2\sqrt{2} [/tex] and [tex] y = \sqrt{2}[/tex], we have: [tex] (2\sqrt{2})^\sqrt^{^2^}[/tex]
It is proven because, in scenario
i) x is rational and y is irrational
ii) x is irrational and y is rational
iii) x and y are irrational
2) Prove tha x² is irrational, then x is irrational.
Use contradiction here.
Thus, x² is irrational and x is rational.
[tex] x =\frac{b}{a} [/tex] when x is rational, a & b are integers.
Therefore, [tex] x^2 =\frac{b^2}{a^2} [/tex]. This x² is rational.
This contradicts the statement that x² is irrational.
Therefore, if x² is irrational, x is also irrational.
Rebecca is a real estate agent who would like to find evidence supporting the claim that the population mean market value of houses in the neighborhood where she works is greater than $250,000. To test the claim, she randomly selects 35 houses in the neighborhood and finds that the sample mean market value is $259,860 with a sample standard deviation of $24.922. The test statistic t for a hypothesis test of H0 : μ = 250.000 versus Ha : μ > 250.000 is t 2.34 , which has 34 degrees of freedom. If 0.01
A) Fail to reject the null hypothesis that the true population mean market value of houses in the neighborhood where Rebecca works is equal to $250,000.
B) Reject the null hypothesis that the true population mean market value of houses in the neighborhood where Rebecca works is equal to $250,000.
C) There is enough evidence at the α-: 0.05 level of significance to support the claim that the true population mean market value of houses in the neighborhood where Rebecca works is greater than $250,000.
D) There is not enough evidence at the α-_ 0.05 level of significance to suggest that the true population mean market value of houses in the neighborhood where Rebecca works is not equal to $250,000.
Answer:
There is enough evidence at the α-: 0.05 level of significance to support the claim that the true population mean market value of houses in the neighborhood where Rebecca works is greater than $250,000.
Step-by-step explanation:
We are given that Rebecca randomly selects 35 houses in the neighborhood and finds that the sample mean market value is $259,860 with a sample standard deviation of $24.922.
Let [tex]\mu[/tex] = population mean market value of houses in the neighborhood.
So, Null Hypothesis, [tex]H_0[/tex] : [tex]\mu[/tex] = $250,000 {means that the population mean market value of houses in the neighborhood where she works is equal to $250,000}
Alternate Hypothesis, [tex]H_A[/tex] : [tex]\mu[/tex] > $250,000 {means that the population mean market value of houses in the neighborhood where she works is greater than $250,000}
The test statistics that would be used here One-sample t-test statistics because we don't know about population standard deviation;
T.S. = [tex]\frac{\bar X-\mu}{\frac{s}{\sqrt{n} } }[/tex] ~ [tex]t_n_-_1[/tex]
where, [tex]\bar X[/tex] = sample mean market value = $259,860
s = sample standard deviation = $24,922
n = sample of houses = 35
So, the test statistics = [tex]\frac{259,860-250,000}{\frac{24,922}{\sqrt{35} } }[/tex] ~ [tex]t_3_4[/tex]
= 2.34
The value of t-test statistic is 2.34.
Also, P-value of the test statistics is given by;
P-value = P([tex]t_3_4[/tex] > 2.34) = 0.0137
Since our P-value is less than the level of significance as 0.0137 < 0.05, so we have sufficient evidence to reject our null hypothesis as it will fall in the rejection region due to which we reject our null hypothesis.
Therefore, we conclude that the population mean market value of houses in the neighborhood where she works is greater than $250,000.
this is a grade 4 maths question. i need help with doing a model from this question as well. thank you! —————————————————- a rope was cut into 2 pieces. The first piece was twice the length of the second piece. If the first piece was 5m 50cm long what was the length of the rope before it was cut
Answer:825cm
Step-by-step explanation:550cm/2=275cm
275*3=825cm
To assess the accuracy of a laboratory scale, a standard weight known to weigh 1 gram is repeatedly weighed a total of n times How large should n be so that a 95% confidence interval for µ has a margin of error of ± 0.0001?
Answer:
[tex]n=(\frac{1.960(1)}{0.0001})^2 =384160000[/tex]
So the answer for this case would be n=384160000 rounded up to the nearest integer
Step-by-step explanation:
We know the following info:
[tex] ME = 0.0001[/tex] represent the margin of error desired
[tex] \sigma= 1[/tex] we assume that the population deviation is this value
The margin of error is given by this formula:
[tex] ME=z_{\alpha/2}\frac{\sigma}{\sqrt{n}}[/tex] (a)
And on this case we have that ME =0.0001 and we are interested in order to find the value of n, if we solve n from equation (a) we got:
[tex]n=(\frac{z_{\alpha/2} \sigma}{ME})^2[/tex] (b)
The critical value for 95% of confidence interval now can be founded using the normal distribution. If we use the normal standard distribution or excel we got: [tex]z_{\alpha/2}=1.960[/tex], replacing into formula (b) we got:
[tex]n=(\frac{1.960(1)}{0.0001})^2 =384160000[/tex]
So the answer for this case would be n=384160000 rounded up to the nearest integer
What are the zeros of f(x) = x^2 + x - 20?
A. x= -4 and x = 5
B. x= -2 and x = 10
C. x= -5 and x = 4
O D. x= -10 and x = 2
All math teachers are smart. Ms. Smith is your math teacher, so she is smart. What type of reasoning is this? inductive or deductive
Answer:
I believe it is Inductive Reasoning.
Step-by-step explanation:
Inductive Reasoning is a type of logical thinking that involves forming generalizations based on specific incidents you've experienced, observations you've made, or facts you know to be true or false.
Deductive Reasoning is a basic form of valid reasoning.
When $\frac{1}{1111}$ is expressed as a decimal, what is the sum of the first 40 digits after the decimal point?
Answer:
90
Step-by-step explanation:
1/1111= 0. (0009) cycles of 0009 after decimal point (one 9 per 4 digits)
Number of digits 9:
40/4= 1010*9= 90Answer:
90
Step-by-step explanation:
What is g(x)?
5-
X
10
-10
Answer: g(x)= -x^2
Step-by-step explanation:
BRO THIS IS THE MOST BASIC ALGEBRA 1 !?!?!?!?!?!?!?!
box + box + box equals to 30
OPTIONS (1,3,5,7,9,11,13,15)
Step-by-step explanation:
[tex] \boxed{3!} + \boxed{9 }+ \boxed{15} = 30 \\ \because \: 3! = 3 \times 2 \times 1 = 6 \\ \therefore \: 6 + 9 + 15 = 30[/tex]
Find the common ratio for this geometric sequence. 243, 27, 3, 1/3, 1/27.
Answer:
1/9
Step-by-step explanation:
Since each next term is 1/9 of the last, the common ratio is 1/9. This can be confirmed by the fact that 243*1/9=27, 27*1/9=3, 3*1/9=1/3, and so on. Hope this helps!
which of the following is equivalent to this?
a: b over a divided by d over c
b: a over b divided by d over c
c: b over a divided by d over c
d: b over a divided by c over d
please help me!
Answer:
b: a over b divided by do over c
Step-by-step explanation:
You can solve this by plugging in numbers for each variable.
For example: a=1, b=4, c=1, d=2
1/4 ÷ 1/2 = 0.125
If you plug in the numbers for all the equations listed, only 1/4 ÷ 2/1 = 0.125.
Please answer this correctly
Answer:
yes
Step-by-step explanation:
not every person is going to have the same opinion, so it is yes.
// have a great day //
Answer:
Yes, because if Pedro asked them the question "what do you think of public transportation?" the majority would probably say that they like it or something along those lines. This is biased because there may be other city inhabitants who don't think very highly of public transportation. Basically, what I'm trying to say is that not everyone will have the same opinion.
How do I solve 24-27?
Answer:
-3
Step-by-step explanation:
You find the difference between the numbers, which is 3. Then you make it negative since 24 is less than 27.
george cut a cake into 8 equal pieces. what is the unit fraction for the cake
Answer: 1/8
Step-by-step explanation:
Unit Fractions: A unit fraction is a rational number written as a fraction where the numerator is one and the denominator is a positive integer. A unit fraction is therefore the reciprocal of a positive integer, 1/n.
Example of Unit Fractions: 1/1, 1/2, 1/3, 1/4 ,1/5, etc.
Hope this helps! Please mark as brainliest!
The unit fraction of the cake is 1/8
What is a unit fraction?A unit fraction is a rational number written as a fraction where the numerator is one and the denominator is a positive integer.
A unit fraction is therefore the reciprocal of a positive integer, 1/n.
Examples are 1/1, 1/2, 1/3, 1/4, 1/5, etc.
Given that, George cut a cake into 8 equal pieces, we need to find the unit fraction for the cake
Since, George cut the cake in 8 equal pieces so, 1 part will be shown by 1/8 of the cake, that mean 1/8 is one unit of the cake, we can say that 1/8 is the unit of the whole cake.
Hence, the unit fraction of the cake is 1/8
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The function h(t) = –16t2 + 28t + 500 represents the height of a rock t seconds after it is propelled by a slingshot.
What does h(3.2) represent?
the height of the rock 3.2 seconds before it reaches the ground
the time it takes the rock to reach the ground, or 3.2 seconds
the time it takes the rock to reach a height of 3.2 meters
the height of the rock 3.2 seconds after it is propelled
Answer:
h(3.2) represents the height of the rock 3.2 seconds after it is propelled. Remember, h(t) represents the height of a rock t seconds after it is propelled.
Answer:
D
Step-by-step explanation:
the height of the rock 3.2 seconds before it reaches the ground
the time it takes the rock to reach the ground, or 3.2 seconds
the time it takes the rock to reach a height of 3.2 meters
the height of the rock 3.2 seconds after it is propelled
Teaching descriptive statistics. A study compared five different methods for teaching descriptive statistics. The five methods were traditional lecture and discussion, programmed textbook instruction, programmed text with lectures, computer instruction, and computer instruction with lectures. 45 students were randomly assigned, 9 to each method. After completing the course, students took a 1-hour exam.
a. What are the hypotheses for evaluating if the average test scores are different for the different teaching methods?
b. What are the degrees of freedom associated with the F-test for evaluating these hypotheses?
c. Suppose the p-value for this test is 0.0168. What is the conclusion?
Answer:
Step-by-step explanation:
a. The hypotheses are:
Null hypothesis: the average test scores are the same for the different teaching methods.
Alternative hypothesis: the average test scores are different for the different teaching methods.
b. To determine the degree of freedom for the F test: we must find two sources of variation such that we have two variances. The two sources of variation are: Factor (between groups) and the error (within groups) and add this up. Or use (N - 1). N is number in sample
c. With a p value of of 0.0168 and using a standard significance level of 0.05, we will reject the null hypothesis as 0.0168 is less than 0.05 and conclude that the average test scores are different for the different teaching methods.
The probability a person has read a book in the past year is 0.81. The probability a person is considered a millennial is 0.28. The probability a person has read a book in the past year and is considered a millennial is 0.25
(a) Find P(Millennial | Read a Book).
(b) Find P(Not Millennial | Did Not Read a Book).
(c) Are being considered a millennial and having read a book in the past year independent events? Justify your answer mathematically.
Answer:
(a) P(Millennial | Read a Book) = 0.3086
(b) P( Not Millennial | Did Not Read a Book) = 0.8421
(c)
P(Millennial and Read a Book) = P(Read a Book) × P(Millennial)
0.25 = 0.81 × 0.28
0.25 ≠ 0.2268
Since the relation doesn't hold true, therefore, being considered a millennial and having read a book in the past year are not independent events.
Step-by-step explanation:
The probability a person has read a book in the past year is 0.81.
P(Read a Book) = 0.81
The probability a person is considered a millennial is 0.28.
P(Millennial) = 0.28
The probability a person has read a book in the past year and is considered a millennial is 0.25.
P(Millennial and Read a Book) = 0.25
(a) Find P(Millennial | Read a Book)
Recall that Multiplicative law of probability is given by
P(A ∩ B) = P(B | A) × P(A)
P(B | A) = P(A ∩ B) / P(A)
For the given case,
P(Millennial | Read a Book) = P(Millennial and Read a Book) / P(Read a Book)
P(Millennial | Read a Book) = 0.25 / 0.81
P(Millennial | Read a Book) = 0.3086
(b) Find P(Not Millennial | Did Not Read a Book)
P( Not Millennial | Did Not Read a Book) = P(Not Millennial and Did Not Read a Book) / P(Did Not Read a Book)
Where
∵ P(A' and B') = 1 - P(A or B)
P(Not Millennial and Did Not Read a Book) = 1 - P(Millennial or Read a Book)
∵ P(A or B) = P(A) + P(B) - P(A and B)
P(Millennial or Read a Book) = P(Read a Book) + P(Millennial) - P(Millennial and Read a Book)
P(Millennial or Read a Book) = 0.81 + 0.28 - 0.25
P(Millennial or Read a Book) = 0.84
So,
P(Not Millennial and Did Not Read a Book) = 1 - 0.84
P(Not Millennial and Did Not Read a Book) = 0.16
Also,
∵ P(A') = 1 - P(A)
P(Did Not Read a Book) = 1 - P(Read a Book)
P(Did Not Read a Book) = 1 - 0.81
P(Did Not Read a Book) = 0.19
Finally,
P( Not Millennial | Did Not Read a Book) = P(Not Millennial and Did Not Read a Book) / P(Did Not Read a Book)
P( Not Millennial | Did Not Read a Book) = 0.16/0.19
P( Not Millennial | Did Not Read a Book) = 0.8421
(c) Are being considered a millennial and having read a book in the past year independent events? Justify your answer mathematically.
Mathematically, two events are considered to be independent if the following relation holds true,
P(A and B) = P(A) × P(B)
For the given case,
P(Millennial and Read a Book) = P(Read a Book) × P(Millennial)
0.25 = 0.81 × 0.28
0.25 ≠ 0.2268
Since the relation doesn't hold true, therefore, being considered a millennial and having read a book in the past year are not independent events.
Determine whether the following statement is true or false.
To construct a confidence interval about the mean, the population from which the sample is drawn must be approximately normal.
a. True
b. False
Answer:
Step-by-step explanation:
In constructing a confidence interval about the mean, the central limit theorem is usually applied. This makes it possible to use the normal distribution. As the number of samples is increasing, the distribution tends to be normal. This would require using the z distribution. In the case where the sample size is small, we assume a normal distribution and use the t distribution. Therefore, the given statement is true.