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# Statistic_Test

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1.(TCO 9) The hours of study and the final exam grades have this type of relationship:
ŷ = 7.35(hours) + 34.62. Based on this linear regression equation, estimate the expected grade for a
student spending 8 hours studying. Round your answer to two decimal places. (Points : 6)

58.80

82.25

91.97

93.42
0                    1321066872      MultipleChoice   1

2.(TCO 5) Historical sales records show that 40% of all customers who enter a discount department
store make a purchase. We are interested in calculating the probability that 3 of 5 customers make
purchase. Choose the best answer of the following: (Points : 6)

This is an example of a Poisson probability experiment

This is an example of a Binomial probability experiment

This is neither a Poisson nor a Binomial probability experiment

Not enough information to determine the type of experiment
0                    1321066874      MultipleChoice   4

3.(TCO 5) Microfracture knee surgery has a 75% chance of success on patients with degenerative
knees. The surgery is performed on 5 patients. Find the probability of the surgery being successful on
less than 3 patients?
(Points : 6)

0.103516

0.632813

0.263672

0.087891
0                    1321066876      MultipleChoice   8

(TCO 5) It has been recorded that 10 people get killed by shark attack every year. What is the
4.
probability of having 5 or 6 people get killed by shark attack this year? (Points : 6)

0.130141

0.026484

0.100889

0.067086
0                    1321066880      MultipleChoice   12

5.   (TCO 2) The median teaching hours for a full time faculty at a state university is eight hours per week.
What does this tell you about the typical teaching hours for full time faculty at that university? (Points : 6)

Half of the full time faculties teach less than eight hours per week while half teaches more than
eight hours per week.

The average teaching hours for full time faculty is eight hours per week.

More full time faculty teaches eight hours per week than any other number of teaching hours.

The number of teaching hours for full time faculty in not very consistent because eight is such a
low number.
0             1321066881         MultipleChoice    14

(TCO 6) Assuming that the data are normally distributed with a mean of 25 and a standard deviation of
6.
1.25, what is the z-score for a value of 27? (Points : 6)

2.30

1.60

3.10

-1.60
0             1321066884         MultipleChoice    16

7.(TCO 8) The mean hours of Internet usage by adults in the US in claimed to be 25 hours per week.
A hypothesis test is performed at a level of significance of 0.05 with a P-value of 0.01. Choose the best
interpretation of the hypothesis test. (Points : 6)

Reject the null hypothesis; there is enough evidence to reject the claim that the mean of hours
Internet usage by adults in the US is 25 hours per week.

Reject the null hypothesis; there is enough evidence to support the claim that the mean hours
Internet usage by adults in the US is 25 hours per week.

Fail to reject the null hypothesis; there is not enough evidence to reject the claim that the mean
hours of Internet usage by adults in the US is 25 hours per week.

Fail to reject the null hypothesis; there is not enough evidence to support the claim that the mean
hours of Internet usage by adults in the US is 25 hours per week..
0             1321066889         MultipleChoice    20

8.(TCO 8) A result of an entry level exam reveals that 22% of students fail that exam.
In a hypothesis test conducted at a level of significance of 2%, a P-value of 0.045 was obtained.
Choose the best interpretation of the hypothesis test. (Points : 6)

Fail to reject the null hypothesis; there is not enough evidence to reject the claim that 22% of
students fail the entry level exam.

Fail to reject the null hypothesis; there is not enough evidence to support the claim that 22% of
students fail the entry level exam.

Reject the null hypothesis; there is enough evidence to reject the claim that 22% of students fail
the entry level exam.

Reject the null hypothesis; there is enough evidence to support the claim that 22% of students fail
the entry level exam.
0             1321066891         MultipleChoice    22
9.(TCO 2) You want to buy light bulbs and you want to choose between two vendors. Vendor A’s light
bulbs have a mean life time of 800 hours and a standard deviation of 175 hours. Vendor B’s light bulbs
also have a mean life time of 800 hours, but a standard deviation of 225 hours. You want light bulbs that
have more life time consistency, which vendor will you purchase from? (Points : 6)

Vendor A because you will be more likely get light bulbs with the same life time

Vendor B because you will be more likely get light bulbs with the same life time

Either one because both produce light bulbs with the same mean life time.

Neither one because a mean height of 800 inches is too short for a light bulb.
0                   1321066895       MultipleChoice   25

(TCO 4) A jar contains balls of four different colors; red, blue, yellow and green. The total balls are
10.
divides as 45% red, 35% blue, 15% yellow, and 5% green. If you are to select one ball at random. Find
the expected value of your winning amount if the payments are set to be \$5, \$15, \$25, \$60 for red, blue,
yellow and green ball respectively.

Winning              5       15     25      60
amount

Probability          45%     35%    15%     5%
(Points : 6)

The expected winning amount is \$28.50

The expected winning amount is \$14.25

The expected winning amount is \$25.50

The expected winning amount is \$11.25
0                   1321066897       MultipleChoice   29

(TCO 3) The grades of 20 students are listed below. Use the stem & leaf to determine the shape of
11.
the distribution. Choose the best answer.

4|4
5|68
6|579
7|157889
8|3457889
9|7

(Points : 6)

The data is symmetric

The data is skewed to the right

The data is skewed to the left

The data is bimodal

0                   1321066899       MultipleChoice   53

12.   (TCO 1) A researcher is considering using 90% confidence interval for his research project instead of
95%. What happens to the required sample size if the confidence level is decreased from 95% to 90%
and the same error margin is allowed in each case? (Points : 6)

The sample size remains unchanged

The sample size needs to increase

The sample size needs to decrease

Not enough information is provided to draw a conclusion regarding the sample size in this case.
0               1321066900       MultipleChoice   36

(TCO 6) Horse race time is found to be normally distributed with a mean value of 10 minutes and a
13.
standard deviation of 2 minutes. Horses whose race time is in the top 5% will not be eligible to
participate in a second round. What is the lowers race time that makes a horse losses his eligibility to
participate in a second round? (Points : 6)

13.29

12

6.71

15.29
0               1321066902       MultipleChoice   37

(TCO 5) A class containing 20 students 8 of them are females. In how many ways can we select a
14.
group of 5 male students? (Points : 6)

56

792

6720

95040
0               1321066904       MultipleChoice   41

15.(TCO 6) Research shows that the life time of Everlast automobile tires is normally distributed with a
mean value of 60,000 miles and a standard deviation of 5,000 miles. What is the probability of having a
tire that lasts more than 67,000 miles? (Points : 6)

0.9192

0.0808

1.40

0.0793
0               1321066906       MultipleChoice   45

(TCO 10) A research shows that employee salaries at company XYX, in thousands of dollars, are
16.
given by the equation y-hat= 48.5 + 2.2 a + 1.5 b where ‘a’ is the years of experience, and ‘b’ is the
education level in years. In thousands of dollars, predict the salary for an employee with 5 years
experience and 16 years education level. (Points : 6)

52.5

59.5
83.5

69.5
0                  1321066908    MultipleChoice   46

(TCO 9) For the graph below, choose the statement that best describes the relationship between the
17.
variables.

(Points : 6)

As hours of absences increases, grades decreases.

As hours of absences decreases, grades increases.

As hours of absences increases, grades increases.

There is no relationship between hours of absences and grades.

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(TCO 8) For the following statement, write the null hypothesis and the alternative hypothesis. Also label
1.
which one is the claim.
A car manufacturer claims that their cars makes at least 35 miles per gallon of fuel. (Points : 8)

0                  1321066912    Short            11

2.(TCO 11) A pizza restaurant manager claims that the average home delivery time for their pizza is no
more than 20 minutes. A random sample of 49 home delivery pizzas was collected. The sample mean
was found to be 21.25 minutes and the standard deviation was found to be 4.3 minutes. Is there
evidence to reject the manager’s claim at alpha =.01? Perform an appropriate hypothesis test, showing
the necessary calculations and/or explaining the process used to obtain the results. (Points : 20)
0            1321066913       Essay            126

3.(TCO 5) A multiple choice exam contains 50 questions. Each question has 5 choices, one of which is
correct. We are interested in knowing the probability guessing exactly 18 questions correctly.
(a) Is this a binomial experiment? Explain how you know.
(b) Use the correct formula to find the probability of guessing exactly 18 questions correctly out of the 50
questions. Show your calculations or explain how you found the probability. (Points : 20)

0            1321066915       Essay            101

4.(TCO 6) The monthly utility bills are normally distributed with a mean value of \$160 and a standard
deviation of \$25.
(a) Find the probability of having a utility bill between 120 and 180.
(b) Find the probability of having a utility bill less than \$120.
(c) Find the probability of having a utility bill more than \$210. (Points : 20)
0           1321066916      Essay           52

5.(TCO 8) A Mall manager claims that in average every customer spends \$37 per a single visit to the
mall. To test this claim, you took a sample of 64 customers and found the sample mean to be \$34 and
the sample standard deviation to be \$5. At alpha = 0.05, test the Mall’s manager claim. Perform an
appropriate hypothesis test, showing the necessary calculations and/or explaining the process used to
obtain the results. (Points : 20)

0           1321066917      Essay           124

6.(TCO 7) A bank manager wanted to estimate the mean number of transactions businesses make per
month. For a sample of 60 businesses, he found the mean number of transaction per month to be 38
and the standard deviation to be 8.5 transactions.
(a) Find a 95% confidence interval for the mean number of business transactions per month. Show your
calculations and/or explain the process used to obtain the interval.
(b) Interpret this confidence interval and write a sentence that explains it. (Points : 20)
0            1321066919      Essay            110

7.(TCO 7) A company’s CEO wanted to estimate the percentage of defective product per shipment. In a
sample containing 400 products, he found 25 defective products.
(a) Find a 95% confidence interval for the true proportion of defective product. Show your calculations
and/or explain the process used to obtain the interval.
(b) Interpret this confidence interval and write a sentence that explains it. (Points : 20)

0            1321066920      Essay            113

8.(TCO 2) The ages of 10 students are listed in years: {17,22,19,24,21,23,29,18,22,28 }
(a) Find the mean, median, mode, sample variance, and range.
(b) Do you think that this sample might have come from a normal population? Why or why not? (Points : 20)

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