Answer:
13.9
Step-by-step explanation:
The mean of a set of numbers is the sum divided by the number of terms
Suppose after 2500 years an initial amount of 1000 grams of a radioactive substance has decayed to 75 grams. What is the half-life of the substance? The half-life is:_______.
(A) Less than 600 years
(B) Between 600 and 700 years
(C) Between 700 and 800 years
(D) Between 800 and 900 years
(E) More than 900 years
Answer:
The correct answer is:
Between 600 and 700 years (B)
Step-by-step explanation:
At a constant decay rate, the half-life of a radioactive substance is the time taken for the substance to decay to half of its original mass. The formula for radioactive exponential decay is given by:
[tex]A(t) = A_0 e^{(kt)}\\where:\\A(t) = Amount\ left\ at\ time\ (t) = 75\ grams\\A_0 = initial\ amount = 1000\ grams\\k = decay\ constant\\t = time\ of\ decay = 2500\ years[/tex]
First, let us calculate the decay constant (k)
[tex]75 = 1000 e^{(k2500)}\\dividing\ both\ sides\ by\ 1000\\0.075 = e^{(2500k)}\\taking\ natural\ logarithm\ of\ both\ sides\\In 0.075 = In (e^{2500k})\\In 0.075 = 2500k\\k = \frac{In0.075}{2500}\\ k = \frac{-2.5903}{2500} \\k = - 0.001036[/tex]
Next, let us calculate the half-life as follows:
[tex]\frac{1}{2} A_0 = A_0 e^{(-0.001036t)}\\Dividing\ both\ sides\ by\ A_0\\ \frac{1}{2} = e^{-0.001036t}\\taking\ natural\ logarithm\ of\ both\ sides\\In(0.5) = In (e^{-0.001036t})\\-0.6931 = -0.001036t\\t = \frac{-0.6931}{-0.001036} \\t = 669.02 years\\\therefore t\frac{1}{2} \approx 669\ years[/tex]
Therefore the half-life is between 600 and 700 years
he pulse rates of 179 randomly selected adult males vary from a low of 43 bpm to a high of 115 bpm. Find the minimum sample size required to estimate the mean pulse rate of adult males. Assume that we want 90% confidence that the sample mean is within 3 bpm of the population mean. Complete parts (a) through (c) belo
Answer:
97
Step-by-step explanation:
Given that:
Low = 43bpm
High = 115 bpm
Error = 3
α = 90%
To find the range estimate :
Standard destviation = (high - low) / 4
Standard deviation = (115 - 43) / 4
Standard deviation = 72/4 = 18
The sample size,(n) :
n = [(Zα/2 * sd)/E] ²
2 - tail = (Zα/2) = 1.645
[(Zα/2 * sd)/E] ² = [(1.645 * 18) / 3]² = (29.61/3)²
= 97.41
Sample size = 97
15 tens 7 ones what is the answer?
Answer:
157
Step-by-step explanation:
Answer: 15 tens and 7 ones in standard form would be 157. If you have 15 tens this means that you are adding 10, 15 times or multiplying 10 by 15, which gives you 150.
Step-by-step explanation: Hopefully this helped!
What is the opposite of the opposite of -1.4?
Answer:
-1.4
Step-by-step explanation:
opposite of -1.4 = 1.4
opposite of the opposite of -1.4 = the opposite of 1.4 = -1.4
7 days left until launch of products with $668 left in budget. Need to spend $85 on last day. How many dollars do we spend on remaining days?
Answer:
In total, you have $668.00.
To reserve enough for the last day, you need to subtract the last day's budget:
This means that, for the remaining 6 days in the week, you have $583.00.
Assuming an equal amount is being spent each day, you can calculate the daily budget by dividing the remaining total by the number of days left.
To avoid going over budget, you can spend $97.16 per day for the other six days.
Hope this helps!
Step-by-step explanation:
The set A = {1, 3, 5}. What is a larger set this might be a subset of?
Answer:
Step-by-step explanation:
A larger set that a particular set can be a subset of is a Universal set. A universal set is parent where all other sets are derived from.
For example, given a universal set U = {1,2,3,4,5}, a set A = {1, 3, 5} is said to be a subset of the set U because the elements of set B are contained in the Universal set U.
Also, sets like {1, 4,5} and {3,4,5} can also be regarded as the subset of U since all the elements of the sets can be found in the Universal set U. Hence the correct name of the set is a UNIVERSAL SET
So, the number of maximum subsets we can create from the given set is 8.
Subsets:The subsets of any set consists of all possible sets including its elements and the null set. Let us understand with the help of an example.
Example: Find all the subsets of set A = {1,2,3,4}
Solution: Given, A = {1,2,3,4}
Subsets =
The subsets of any set consisting of all possible sets including its elements and the null set. Let us understand with the help of an example.
Example: Find all the subsets of set A = {1,2,3,4}
{}
{1}, {2}, {3}, {4},
{1,2}, {1,3}, {1,4}, {2,3},{2,4}, {3,4},
{1,2,3}, {2,3,4}, {1,3,4}, {1,2,4}
{1,2,3,4}
So, the formula is [tex]2^n[/tex].
The given set is,
[tex]A = \{1, 3, 5\}[/tex]
Here the number of an element is 3.
So, the maximum number of subsets we can create is,
[tex]2^n=2^3=8[/tex]
Learn more about the topic Subsets:
https://brainly.com/question/17514113
I don't believe I was shown how to complete this
(3)/(5)x = (2)/(5)x + 8
Answer: x=-19
Step-by-step explanation:
Th e expert trail is 750 meters longer than the beginner trail. How long is each trail?
do they give the whole amount of both trails together? then someone would be able to answer this so pls add that
Paul and Seth know that one point on the line
Answer:
what
Step-by-step explanation:
The zeroes of the function are:
A) -2 and 0
B) 0 and 4
C) -2, 0, and 4
Gwendolyn was physically present in the United States for 96 days in 2019, 198 days in 2018, and 66 days in 2017. Under the substantial presence test formula, how many days is Gwendolyn deemed physically present in the United States in 2019 g
Answer:
173 days
Step-by-step explanation:
The formula for substantial presence test is;
SBT = (Total of number of days present in the current tax year) + (1/3)(number of days in the year that was before the tax year) + (1/6)(number of days in the year that was two years before the tax year)
From the question, present tax year is 2019 and number of days is 96 days.
Year before tax year is 2018 and number of days is 198 days
2 years before tax year is 2017 and number of days is 66 days.
Thus;
SBT = 96 + ((1/3)198) + ((1/6)66)
SBT = 173 days
Caleb and Emily are standing 100 yards from each other. Caleb looks up at a 45° angle to see a hot air balloon. Emily looks up at a 60° angle to see the same hot air balloon. Approximately how far is the hot air balloon off the ground?
a) 44.3 yd.
b) 63.4 yd.
c) 73.2 yd.
d) 89.7 yd.
Answer:
B. 63.4 yards.
Step-by-step explanation:
Hannah wants to buy a $460 camera. She can save $35 each week from her paycheck. However, before Hannah can buy the camera, she must give her brother $65 that she owes him. For how many weeks will Hannah need to save before she can pay back her and buy the camera?
Answer:
460+65=525/35=15 15 weeks
The temperature at 6 a.m. was −12°F. At 11 a.m. the temperature was 0°F. Which of the following shows the temperature change from 6 a.m. to 11 am?
Answer:
+12 degrees
Step-by-step explanation:
You never showed a picture, but im pretty sure this is correct
I hope this helped, please mark Brainliest, thank you!
What value of a will make the following equation true?
Answer:
a=16
Step-by-step explanation:
Answer:
A=4
Step-by-step explanation:
Please help with this easy fraction problem <3
18 + 7/9
14 + 7/8
First, rewrite each fraction in terms of a common denominator. 8 and 9 don't share a common multiple until 8 * 9 = 72, so we have
7/9 = (7/9) • (8/8) = (7 • 8)/(9 • 8) = 56/72
7/8 = (7/8) • (9/9) = (7 • 9)/(8 • 9) = 63/72
Next, write each whole number in terms of fractions with the same denominator. We have
18 • 72 = 1296 ==> 18 = 1296/72
14 • 72 = 1008 ==> 14 = 1008/72
Write each mixed number as an improper fraction:
18 + 7/9 = 1296/72 + 56/72 = (1296 + 56)/72 = 1352/72
14 + 7/8 = 1008/72 + 63/72 = (1008 + 63)/72 = 1071/72
If the backpack and book together weigh 18 + 7/9 pounds, and the backpack without the book weighs 14 + 7/8 pounds, then the book alone weighs the difference, call it b :
b = (18 + 7/9) - (14 + 7/8)
b = 1352/72 - 1071/72
b = (1352 - 1071)/72
b = 281/72
Convert this to a mixed number. 72 • 4 = 288, so 72 • 4 - 7 = 281:
b = (72 • 4 - 7)/72
b = (72 • 4)/72 - 7/72
b = 4 - 7/72
b = (3 + 1) - 7/72
b = 3 + (1 - 7/72)
b = 3 + 65/72
Tell me what quadrant this angle is in.
Answer:
Second quadrant
Step-by-step explanation:
[tex] \because \: \frac{ \pi}{2} < \theta < \pi \: bounds \: second \: quadrant \\ \\ \therefore \: \sin \theta = \frac{4}{5 } \: lies \: in \: second \: quadrant.[/tex]
Will give brainliest if correct what is the discriminant of the quadratic equation: (multiple choice)
I want to decorate my room with leaves and turkeys for Thanksgiving. The number of leaves is twenty more than twice the number of turkeys. The number of leaves is ten less than 4 times the number of turkeys. How many of each type of decoration should I use?
Answer:
50 leaves, 15 turkeys
Step-by-step explanation:
set up an equation
l = leaves
t = turkeys
l = 2t+20
l = 4t-10
2t+20=4t-10
30=2t
15=t (so that means that there would be 15 turkey decorations, but we're not done yet)
substitute (either equation):
l = 2(15)+20
l = 30+20
l = 50 (so this means there would be 50 leaves)
hope this helps!
1. Let the test statistics Z have a standard normal distribution when H0 is true. Find the p-value for each of the following situations:
a) H1:μ>μ0,z=1.88
b) H1:μ<μ0,z=−2.75
c) H1:μ≠μ0,z=2.88
2. Let the test statistics T have t distribution when H0 is true. Find the p-value for each of the following situations (provide an interval if the exact one cannot be found using a table):
a) H1:μ>μ0,n=16,t=3.733
b) H1:μ<μ0,df=23,t=−2.500
c) H1:μ≠μ0,n=7,t=−2.250
Answer:
1 a [tex]p -value = 0.030054[/tex]
1b [tex]p -value = 0.0029798[/tex]
1c [tex]p -value = 0.0039768[/tex]
2a [tex]p-value = 0.00099966[/tex]
2b [tex]p-value = 0.00999706[/tex]
2c [tex]p-value = 0.0654412[/tex]
Step-by-step explanation:
Considering question a
The alternative hypothesis is H1:μ>μ0
The test statistics is z =1.88
Generally from the z-table the probability of z =1.88 for a right tailed test is
[tex]p -value = P(Z > 1.88) = 0.030054[/tex]
Considering question b
The alternative hypothesis is H1:μ<μ0
The test statistics is z=−2.75
Generally from the z-table the probability of z=−2.75 for a left tailed test is
[tex]p -value = P(Z < -2.75) = 0.0029798[/tex]
Considering question c
The alternative hypothesis is H1:μ≠μ0
The test statistics is z=2.88
Generally from the z-table the probability of z=2.88 for a right tailed test is
[tex]p -value = P(Z >2.88) = 0.0019884[/tex]
Generally the p-value for the two-tailed test is
[tex]p -value = 2 * P(Z >2.88) = 2 * 0.0019884[/tex]
=> [tex]p -value = 0.0039768[/tex]
Considering question 2a
The alternative hypothesis is H1:μ>μ0
The sample size is n=16
The test statistic is t = 3.733
Generally the degree of freedom is mathematically represented as
[tex]df = n - 1[/tex]
=> [tex]df = 16 - 1[/tex]
=> [tex]df = 15[/tex]
Generally from the t distribution table the probability of t = 3.733 at a degree of freedom of [tex]df = 15[/tex] for a right tailed test is
[tex]p-value = t_{3.733 , 15} = 0.00099966[/tex]
Considering question 2b
The alternative hypothesis is H1:μ<μ0
The degree of freedom is df=23
The test statistic is ,t= −2.500
Generally from the t distribution table the probability of t= −2.500 at a degree of freedom of df=23 for a left tailed test is
[tex]p-value = t_{-2.500 , 23} = 0.00999706[/tex]
Considering question 2c
The alternative hypothesis is H1:μ≠μ0
The sample size is n= 7
The test statistic is ,t= −2.2500
Generally the degree of freedom is mathematically represented as
[tex]df = n - 1[/tex]
=> [tex]df = 7 - 1[/tex]
=> [tex]df = 6[/tex]
Generally from the t distribution table the probability of t= −2.2500 at a degree of freedom of [tex]df = 6[/tex] for a left tailed test is
[tex]t_{-2.2500 , 6} = 0.03272060[/tex]
Generally the p-value for t= −2.2500 for a two tailed test is
[tex]p-value = 2 * 0.03272060 = 0.0654412[/tex]
Can someone who knows Pre Calculus help me on these questions.
Answer:
the answer should be B:12/5
28 points. I need help ASAP please
Answer:
1) Thousands
2) 5
3) ten million
4) 3,000,000
Step-by-step explanation:
Answer:
1. hundred thousands
2. 5
3. ten millions
4. 3,000,000
Step-by-step explanation:
I'm a little confused.
(2y+14.6+3.8)-(34.8m+15.6+2y)
Answer:
5.6
Step-by-step explanation:
You most likely will end up putting it in slope form y=mx+b
(2y+14.6+3.8)-(34.8m+15.6+2y) collect like terms
(2y+18.4)-(34.8m + 15.6 + 2y) = 2.8 + 34.8m
2y-2y= 0
18.4 - 15.6= 2.8
34.8m -0 = 34.8m
2.8 + 34.8m ( I think we should further simplify)
so minus 2.8 on both sides
34.8m = -2.8(divide by 34.8 on both sides)
m = -7/87
Plug in
(2y+14.6+3.8)-(34.8(-7/87)+15.6+2y) collect like terms
(2y+18.4)-(-2.8 + 15.6 + 2y) collect like terms
(18.4)-(12.8)= 5.6
2y-2y = 0
34.8(-7/87)= -2.8
18.4 - 12.8 = 5.6
I need help with a math problem comment if u want i really need help with this
Manuel can walk 5 miles In one hour. At this rate, how many miles can he walk in 8 minutes? Round to the nearest tenth
Answer:0.6666664
Step-by-step explanation:
You take 5 and divide by 60. Then multiply by 8.
2/3 of a mile.
If he can walk 5 MILES a hour, lets use 5/60.
Multiply 5/60 by 8 since each minute he travels 5/60 of a MILE.
You get 0.66(repeating) OR 2/3
What does "a' control in a graph of * f(x) = ax + bx+ c?
Answer:
the stretch or compression of a quadratic, and if it's opening up to down.
Step-by-step explanation:
At a school, there are 120 athletes. The ratio of boy athletes to giri athletes is 3:5. How many of the athletes are girls?
А
75
B
45
с
24
D 5
Answer:
a
Step-by-step explanation:
because there are over half girls and half of 120 is 60 and 75 is over half
Solve: x^2=10
A) x= +5
B) x= +100
C) x= +3.5
D) x= 10 squared
Answer:
D) x=√10
Step-by-step explanation:
√(10)=3.16(approximately )
Question Help When purchasing bulk orders of batteries, a toy manufacturer uses this acceptance sampling plan: Randomly select and test 36 batteries and determine whether each is within specifications. The entire shipment is accepted if at most 2 batteries do not meet specifications. A shipment contains 3000 batteries, and 3% of them do not meet specifications. What is the probability that this whole shipment will be accepted? Will almost all such shipments be accepted, or will many be rejected?
Answer:
The probability is [tex]P(X \le 2 ) = 0.9072[/tex]
The company will accept 90.72% of the shipment and will reject [tex](100 -90.72) = 9.2\%[/tex] of the shipment , so many of the shipment are rejected
Step-by-step explanation:
From the question we are told that
The sample size is n = 36
The proportion that did not meet the requirement is [tex]p = 0.03[/tex]
Generally the probability that the whole shipment is accepted is equivalent to the probability that there is at most 2 batteries that do not meet the requirement , this is mathematically represented as
[tex]P(X \le 2 ) = [ P(X = 0 ) + P(X = 1 ) + P(X = 0)][/tex]
=> [tex]P(X \le 2 ) = [ [^{n}C_0 * (p)^{0} *(1-p)^{n-0} ] + [^{n}C_1 * (p)^{1} *(1-p)^{n-1} ] + [^{n}C_2 * (p)^{2} *(1-p)^{n-2} ]][/tex]
Here C stands for Combination (so we will be making the combination function in our calculators )
So
=> [tex]P(X \le 2 ) = [ [^{36}C_0 * (0.03)^{0} *(1-0.03)^{36-0} ] + [^{36}C_1 * (0.03)^{1} *(1-0.03)^{36-1} ] + [^{36}C_2 * (0.03)^{2} *(1-0.03)^{36-2} ]][/tex]
=> [tex]P(X \le 2 ) = [ [1 * 1 * 0.3340 ] + [36* 0.03 *0.3444 ] + [630 * 0.0009 *(0.355 ]][/tex]
=>[tex]P(X \le 2 ) = 0.9072[/tex]
The company will accept 90.72% of the shipment and will reject [tex](100 -90.72) = 9.2\%[/tex] of the shipment , so many of the shipment are rejected