Answer:
The total number of ways to select 2 CDs from 8 CDs is 28.
In a recent study of 42 eighth graders, the mean number of hours per week that they watched television was 19.6. Assume the population standard deviation is 5.8 hours. Find the 98% confidence interval for the population mean.
a. (17.5, 21.7)
b. (14.1, 23.2)
c. (18.3, 20.9)
d. (19.1, 20.4)
Answer:
[tex]19.6-2.42\frac{5.8}{\sqrt{42}}=17.43[/tex]
[tex]19.6+2.42\frac{5.8}{\sqrt{42}}=21.77[/tex]
And the best option for this case would be:
a. (17.5, 21.7)
Step-by-step explanation:
Information given
[tex]\bar X= 19.6[/tex] represent the sample mean
[tex]\mu[/tex] population mean
[tex]\sigma= 5.8[/tex] represent the population deviation
n=42 represent the sample size
Confidence interval
The confidence interval for the mean is given by the following formula:
[tex]\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}[/tex] (1)
The degrees of freedom, given by:
[tex]df=n-1=42-1=41[/tex]
Since the Confidence is 0.98 or 98%, the significance would be [tex]\alpha=0.02[/tex] and [tex]\alpha/2 =0.1[/tex], and the critical value would be [tex]t_{\alpha/2}=2.42[/tex]
Replacing we got:
[tex]19.6-2.42\frac{5.8}{\sqrt{42}}=17.43[/tex]
[tex]19.6+2.42\frac{5.8}{\sqrt{42}}=21.77[/tex]
And the best option for this case would be:
a. (17.5, 21.7)
Answer:
The 98% confidence interval for the population mean is between 17.5 hours and 21.7 hours.
What is the surface area of this regular pyramid? A. 230 in2 B. 304 in2 C. 480 in2 D. 544 in2
Answer:
B: 304in^2
Step-by-step explanation:
One triangle face: (8)(15) ÷ 2 = 60
Four triangle faces: 60 x 4 = 240
Bottom Face: (8)(8) = 64
Total Surface Area: Four triangle faces + Bottom Face
Total Surface Area: 240 + 64
Total Surface Area: 304in^2
Consider the accompanying matrix as the augmented matrix of a linear system. State in words the next two elementary row operations that should be performed in the process of solving the system.
(1 -4 4 0 -2
0 2 -6 0 5
0 0 1 2 - 4
0 0 4 5 -1]
(Type an integer or a simplified fraction)
A. Replace row 4 by its sum with - 4 times row 3.
(Type an integer or a simplified fraction)
B. Replace row 2 by its sum with times row 4.
(Type an integer or a simplified fraction.)
C. Interchange row 3 and row 2.
Answer:
The correct option is (A)
A. Replace row 4 by its sum with - 4 times row 3.
[tex]\left[\begin{array}{ccccc}1&-4&4&0&-2\\0&2&-6&0&5\\0&0&1&2&-4\\0&0&0&-3&15\end{array}\right][/tex]
w = 8
x = 17/2
y = 6
z = -5
Step-by-step explanation:
The given matrix is
[tex]\left[\begin{array}{ccccc}1&-4&4&0&-2\\0&2&-6&0&5\\0&0&1&2&-4\\0&0&4&5&-1\end{array}\right][/tex]
To solve this matrix we need to create a zero at the 4th row and 3rd column which is 4 at the moment.
Multiply 3rd row by -4 and add it to the 4th row.
Mathematically,
[tex]R_4 = R_4 - 4R_3[/tex]
So the correct option is (A)
A. Replace row 4 by its sum with - 4 times row 3.
So the matrix becomes,
[tex]\left[\begin{array}{ccccc}1&-4&4&0&-2\\0&2&-6&0&5\\0&0&1&2&-4\\0&0&0&-3&15\end{array}\right][/tex]
Now the matrix may be solved by back substitution method.
Bonus:
The solution is given by
Eq. 1
-3z = 15
z = -15/3
z = -5
Eq. 2
y + 2z = -4
y + 2(-5) = -4
y - 10 = -4
y = -4 + 10
y = 6
Eq. 3
2x - 6y + 0z = 5
2x - 6(6) = 5
2x - 12 = 5
2x = 12 + 5
2x = 17
x = 17/2
Eq. 4
w - 4x + 4y + 0z = -2
w - 4(17/2) + 4(6) = -2
w - 34 + 24 = -2
w - 10 = -2
w = -2 + 10
w = 8
If x=3 then what is y the equation is 2x -y=5 if you have the answer lets d a t e I m f e m a l e. T a n g ie_man 18 snap without spaces.
Answer:
y = 1Step-by-step explanation:
Given the equation, 2x- y = 5, if x = 3, to get y we will simply substitute the value of x into the expression given as shown;
[tex]2x - y = 5\\\\Substituting \ x = 3\ into \ the \ equation\\\\2(3) - y = 5\\\\6 - y = 5\\\\subtracting\ 6\ from\ both\ sides\\\\6-6-y = 5- 6\\\\-y = -1\\\\multiplying\ both\ sides\ by \ -1\\-(-y) = -(-1)\\\\y = 1[/tex]
Hence, the value of y is 1
A concession-stand manager buys bottles of water and soda to sell at a football game. The manager needs to buy a total of 4,500 drinks and have 25% more water than soda. Let w be the number of bottles of water and let s be the number of bottles of soda. Create a system of equations for w in terms of s that the manager could use to find out how many bottles of water and soda to bu
Answer: The equations are
w + s = 4500
2.25s = 4500
Step-by-step explanation:
Let w represent the number of bottles of water that the football manager bought.
Let s represent the number of bottles of soda that the football manager bought.
The manager needs to buy a total of 4,500 drinks. This means that
w + s = 4500
He also needs to have 25% more water than soda.
25% of soda = 25/100 × s = 0.25s
25% more of water than soda = s + 0.25s = 1.25s
The equation would be
1.25s + s = 4500
2.25s = 4500
Help me pls I need help
Answer:
C
Step-by-step explanation:
If two lines are parallel, their slopes are the same.
Since the slope of line l is 4/9, this means that the slope of line m must also be 4/9.
Answer:
C. 4/9
Step-by-step explanation:
Parallel lines have equal slopes.
Since line l and line m are parallel, then their slopes must be the same.
[tex]m_{l} =m_{m}[/tex]
We know that the slope of line l is 4/9
[tex]\frac{4}{9} = m_{m}[/tex]
Line l has a slope of 4/9, therefore line m must also have a slope of 4/9.
The correct answer is C. 4/9
Follow the properties of the equality given for the steps to solve the following equation:
-3(x-4)+5=-x-3
(answers and steps in photo)
Answer:
Step-by-step explanation:
-3x+12+5= -x-3 -3x+17 = -x-317 = 2x-320 =2xx=10A study of the amount of time it takes a mechanic to rebuild the transmission for a 2010 Chevrolet Colorado shows that the mean is 8.4 hours and the standard deviation is 1.8 hours. If 40 mechanics are randomly selected, find the probability that their mean rebuild time is less than 8.9 hours.
Answer:
96.08% probability that their mean rebuild time is less than 8.9 hours.
Step-by-step explanation:
To solve this question, we need to understand the normal probability distribution and the central limit theorem.
Normal probability distribution
When the distribution is normal, we use the z-score formula.
In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the zscore of a measure X is given by:
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
Central Limit Theorem
The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].
For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.
In this question:
[tex]\mu = 8.4, \sigma = 1.8, n = 40, s = \frac{1.8}{\sqrt{40}} = 0.2846[/tex]
Find the probability that their mean rebuild time is less than 8.9 hours.
This is the pvalue of Z when X = 2.9.
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
By the Central Limit Theorem
[tex]Z = \frac{X - \mu}{s}[/tex]
[tex]Z = \frac{2.9 - 2.4}{0.2846}[/tex]
[tex]Z = 1.76[/tex]
[tex]Z = 1.76[/tex] has a pvalue of 0.9608
96.08% probability that their mean rebuild time is less than 8.9 hours.
What is the greatest common factor of 36 and 44?
Answer:
GCF - 4
Step-by-step explanation:
36 - 1, 2, 3, 4, 6, 9, 12, 18, 36
44 - 1, 2, 4, 11, 44
Hope this helps! :)
The time to assemble the first unit on a production line is 8 hours. The learning rate is 0.81. Approximately how long will it take for the seventh unit to be assembled?
Answer:
4.428 hours
Step-by-step explanation:
If the learning rate is 0.81, the slope of the learning curve is:
[tex]b=\frac{ln(0.81)}{ln(2)} \\b=-0.304[/tex]
The time it takes to produce the n-th unit is:
[tex]T_n=T_1*n^b[/tex]
If T1 = 8 hours, the time required to produce the seventh unit will be:
[tex]T_n=8*7^{-0.304}\\T_n=4.428\ hours[/tex]
It will take roughly 4.428 hours.
Identify the parts (include: terms, coefficients, variables and
constants) of the following expression and translate it into a
verbal expression:
2(3x - 2y) + 7
Answer:
x=9
Step-by-step explanation:
3x subtracted by 2y
is 1 then 1 multiplied by 2 is 2 then 7 + 2 is 9
PEMDAS
As part of a larger project to study the behavior of stressed-skin panels, a structural component being used extensively in North America, an article reported on various mechanical properties of Scotch pine lumber specimens. Data on the modulus of elasticity (MPa) obtained 1 minute after loading in a certain configuration and 4 weeks after loading for the same lumber specimens is presented here.
Observatio 1 min 4 Week Difference
1 16,620 9,110 1380
2 17,300 13,250 3370
3 15,480 14,720 2580
4 12,970 12,740 2740
5 17,260 10,120 2850
6 13,400 14,570 2690
7 13,900 11,220 2180
8 13,630 11,100 2800
9 13,260 11,420 2210
10 14,370 10,910 2350
11 11,700 12,110 2260
12 15,470 8,620 3080
13 17,840 12,590 2880
14 14,070 15,090 2750
15 14,760 10,550 3520
Required:
Calculate and interpret an upper confidence bound for the true average difference between 1-minute modulus and 4-week modulus; first check the plausibility of any necessary assumptions. (Use α = 0.05. Round your answer to the nearest whole number.)
Answer:
The upper confidence bound for the true average difference between 1-minute modulus and 4-week modulus is 2933.82.
Step-by-step explanation:
Compute the mean difference and standard deviation of the difference as follows:
[tex]\bar d=\frac{1}{n}\sum d_{i}=\frac{1}{15}\times [1380+3370+2580+...+3520]=2642.67\\\\S_{d}=\sqrt{\frac{1}{n-1}\sum (d_{i}-\bar d)^{2}}\\=\sqrt{\frac{1}{15-1}[(1380-2642.67)^{2}+(3370-2642.67)^{2}+...}=525.69[/tex]
The degrees of freedom is:
df = n - 1
= 15 - 1
= 14
Th critical value of t is:
[tex]t_{\alpha/2, (n-1)}=t_{0.05/2, 14}=2.145[/tex]
*Use a t-table.
Compute the upper confidence bound for the true average difference between 1-minute modulus and 4-week modulus as follows:
[tex]\text{Upper Confidence Bound}=\bar d+t_{\alpha/2, (n-1)}\cdot \frac{S_{d}}{\sqrt{n}}[/tex]
[tex]=2642.67+2.145\cdot \frac{525.69}{\sqrt{15}}\\\\=2642.67+291.15\\\\=2933.82[/tex]
Thus, the upper confidence bound for the true average difference between 1-minute modulus and 4-week modulus is 2933.82.
The function f(x) = 2x^3 + 3x^2 is:
(a) even
(b) odd
(c) neither
(d) even and odd
Answer:
neither
Step-by-step explanation:
First we must determine if both x and -x are in the domain of the function
since it is a polynomial function our first condition is satisfied
Then we should calculate the image of -x :
2x(-x)^3 + 3*(-x)² = -2x^3+3x²
it is not equal to f(x) nor -f(x)
The graph of y =ex is transformed as shown in the graph below. Which equation represents the transformed function?
Answer:
B. e^x+3
Step-by-step explanation:
Y=e^x
the graph is moving 3 units up
y= y+3
y=e^x+3
answer = y=e^x+3
Answer: B
Step-by-step explanation:
Translate the following argument in a standard form categorial syllogims then use venn diagram or rules for syllogim to determine whether each is valid or invalid.
All of the movies except the romantic comedies were exciting. Hence, the action films were exciting,because none of them is a romantic comedies.
Answer:
couldnt tell you
Step-by-step explanation:
jkj
The average daily rainfall for the past week in the town of Hope Cove is normally distributed, with a mean rainfall of 2.1 inches and a standard deviation of 0.2 inches. If the distribution is normal, what percent of data lies between 1.9 inches and 2.3 inches of rainfall? a) 95% b) 99.7% c) 34% d) 68%
Answer:
D
Step-by-step explanation:
We calculate the z-score for each
Mathematically;
z-score = (x-mean)/SD
z1 = (1.9-2.1)/0.2 = -1
z2 = (2.3-2.1)/0.2 = 1
So the proportion we want to calculate is;
P(-1<x<1)
We use the standard score table for this ;
P(-1<x<1) = P(x<1) -P(x<-1) = 0.68269 which is approximately 68%
Answer:
68
Step-by-step explanation:
The valve was tested on 250 engines and the mean pressure was 7.3 pounds/square inch (psi). Assume the population standard deviation is 0.8. The engineer designed the valve such that it would produce a mean pressure of 7.2 psi. It is believed that the valve does not perform to the specifications. A level of significance of 0.05 will be used. Find the value of the test statistic. Round your answe
Answer:
Step-by-step explanation:
We would set up the hypothesis test. This is a test of a single population mean since we are dealing with mean
For the null hypothesis,
H0: µ = 7.2
For the alternative hypothesis,
H1: µ ≠ 7.2
This is a two tailed test.
Since the population standard deviation is given, the test statistic would be the z score determined from the normal distribution table. The formula is
z = (x - µ)/(σ/√n)
Where
x = sample mean
µ = population mean
σ = population standard deviation
n = number of samples
From the information given,
µ = 7.2
x = 7.3
σ = 0.8
n = 250
z = (7.3 - 7.2)/(0.8/√250) = 1.976
Test statistic is 1.976
Please help asap!!!!!!!
Answer:Yes indeed!
Step-by-step explanation:
Your right!
pls help help help hepl
Answer:
C
Step-by-step explanation:
undefined slope means tat the denominator=0 in the equation
m=y2-y1/x2-x1
A: m=-1-1/1+1=-2
B;2-2/2+2=0
C: 3+3/-3+3 = 6/0 undefined
D: 4+4/4+4=1
Solve the quadratic equation x2 + 14x = 51 by completing the square.
Question 3 options:
A)
x = –17, x = –3
B)
x = –17, x = 3
C)
x = 3, x = 17
D)
x = –3, x = 17
Answer:
B
Step-by-step explanation:
Given
x² + 14x = 51
To complete the square
add ( half the coefficient of the x- term )² to both sides
x² + 2(7)x + 49 = 51 + 49 , that is
(x + 7)² = 100 ( take the square root of both sides )
x + 7 = ± [tex]\sqrt{100}[/tex] = ± 10 ( subtract 7 from both sides )
x = - 7 ± 10
Thus
x = - 7 - 10 = - 17
x = - 7 + 10 = 3
Maya is solving the quadratic equation by completing the square. 4x2 + 16x + 3 = 0 What should Maya do first?
Maya should Isolate the variable x² option (A) Isolate the variable x² is correct.
What is a quadratic equation?Any equation of the form [tex]\rm ax^2+bx+c=0[/tex] where x is variable and a, b, and c are any real numbers where a ≠ 0 is called a quadratic equation.
As we know, the formula for the roots of the quadratic equation is given by:
[tex]\rm x = \dfrac{-b \pm\sqrt{b^2-4ac}}{2a}[/tex]
The complete question is:
Maya is solving the quadratic equation by completing the What should Maya do first? square.
4x² + 16x + 3 = 0
Isolate the variable x².Subtract 16x from both sides of the equation.Isolate the constant.Factor 4 out the variable terms.We have a quadratic equation:
4x² + 16x + 3 = 0
To make the perfect square
Maya should do first:
Isolate the variable x²
To make the coefficient of x² is 1.
4(x² + 4x + 3/4) = 0
x² + 4x + 3/4 = 0
x² + 4x + 2² - 2² + 3/4 = 0
(x + 2)² - 4 + 3/4 = 0
(x + 2)² = 13/4
x + 2 = ±√(13/4)
First, take the positive and then the negative sign.
x = √(13/4) - 2
x = -√(13/4) - 2
Thus, Maya should Isolate the variable x² option (A) Isolate the variable x² is correct.
Learn more about quadratic equations here:
brainly.com/question/2263981
#SPJ5
can someone help me with this please?!?
Answer:
The answer is 60cm^2.
hope it helps..
Researchers studied the mean egg length (in millimeters) for a particular bird population. After a random sample of eggs, they obtained a 95% confidence interval of (45,60) in millimeters. In the context of the problem, which of the following interpretations is correct, if any?
A. We are 95% sure that an egg will be between 45 mm and 60 mm in length.
B. For this particular bird population, 95% of all birds have eggs between 45 mm and 60 mm.
C. We are 95% confident that the mean length of eggs for this particular bird population is between 45 mm and 60 mm.
D. We are 95% confident that the mean length of eggs in the sample is between 45 mm and 60 mm.
E. None of the above is a correct interpretation.
Answer:
C. We are 95% confident that the mean length of eggs for this particular bird population is between 45 mm and 60 mm.
Step-by-step explanation:
Confidence interval can be defined as a range of values so defined that there is a specified probability that the value of a parameter lies within it.
For 95% confidence interval, it means that we are 95% confident that the mean of the population is between the given upper and lower bounds of the confidence interval.
For the case above, the interpretation of the 95% confidence interval is that we are 95% confident that the mean length of eggs for this particular bird population is between 45 mm and 60 mm.
How do you write 0.0026 in scientific notation? ___× 10^____
Answer:
It's written as
[tex]2.6 \times {10}^{ - 3} [/tex]
Hope this helps you
Answer:
2.6 × 10⁻³
Step-by-step explanation:
To write a number in scientific notation, move the decimal to the right or left until you reach a number that is 1 or higher.
In the decimal 0.0026, the first number that is 1 or higher is 2.
0.0026 ⇒ 2.6
When trying to figure out the exponent, here are some things to keep in mind:
- when you move the decimal to the right, the exponent is negative
- when you move the decimal to the left, the exponent is positive
You moved the decimal to the right three places. So the exponent will be -3.
The result is 2.6 × 10⁻³.
Hope this helps. :)
divide 15 root 20 by 6 root 125
Answer:
15√20/6√125
=√20/√5
=2
Step-by-step explanation:
Can anyone please explain? Need some help :)
A regular hexagon is inscribed in a circle with a diameter of 12 units. Find the area of the hexagon. Round your answer to the nearest tenth. (there's no picture included)
Answer:
93.5 square units
Step-by-step explanation:
Diameter of the Circle = 12 Units
Therefore:
Radius of the Circle = 12/2 =6 Units
Since the hexagon is regular, it consists of 6 equilateral triangles of side length 6 units.
Area of the Hexagon = 6 X Area of one equilateral triangle
Area of an equilateral triangle of side length s = [tex]\dfrac{\sqrt{3} }{4}s^2[/tex]
Side Length, s=6 Units
[tex]\text{Therefore, the area of one equilateral triangle =}\dfrac{\sqrt{3} }{4}\times 6^2\\\\=9\sqrt{3} $ square units[/tex]
Area of the Hexagon
[tex]= 6 X 9\sqrt{3} \\=93.5$ square units (to the nearest tenth)[/tex]
In her backyard, Mary is planting rows of tomatoes. To plant a row of tomatoes, mary needs 20/13 square feet. There are 40 square feet in Mary's backyard, so how many rows of tomatoes can mary plant??
Answer:
26 rows
Step-by-step explanation:
[tex]number \: of \: rows \\ = \frac{40}{ \frac{20}{13} } \\ \\ = \frac{40 \times 13}{20} \\ \\ = 2 \times 13 \\ \\ = 26 \: [/tex]
Can somebody please help me with this question?
Answer: 6x^2
Step-by-step explanation:
The area of a triangle is 1/2bh
Thus, simply multiply 2x*3x = 6x^2
Hope it helps <3
Answer:
[tex]3 {x}^{2} [/tex]Solution,
Base(b)= 3x
Height(h) = 2x
Now,
Finding the area of triangle:
[tex] \frac{1}{2} \times b \times h[/tex]
[tex] \frac{1}{2} \times 3x \times 2x[/tex]
[tex] \frac{1}{2} \times 6 {x}^{2} [/tex]
[tex]3 {x}^{2} [/tex]
Hope this helps....
Good luck on your assignment....
Select two ratios that are equivalent to 7:6
Two ratios that are equal to 7:6 are 14:12 and 21:18, as they are the same, but 7 and 6 are multiplied by the same number (2 in the first, and 3 in the second.)
5c + 16.5 = 13.5 + 10c
Answer:
Hello!
________________________
5c + 16.5 = 13.5 + 10c
Exact Form: c = 3/5
Decimal Form: c = 0.6
Step-by-step explanation: Isolate the variable by dividing each side by factors that don't contain the variable.
Hope this helped you!
Answer:
3000+3d=noods
Step-by-step explanation: