# Statistics Review Questions.

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Choose the best answer to the following questions.

1. (TCO 9) The hours of study and the final exam grades have this type of relationship:

? = 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.

58.80

82.25

91.97

93.42

2. (TCO 5) A company produces electronic equipments claims that 98% of their products never need any kind of maintenance. We selected 10 of their products and we wanted to know the probability that 8 of them never need maintenance. Choose the best answer of the following:

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

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 3 or 4 patients?

0.103516

0.659180

0.762695

0.642875

4. (TCO 5) It has been recorded that 10 people get killed by shark attack every year. What is the probability of having 3 or 4 people get killed by shark attack this year?

0.026484

0.029253

0.018917

0.010336

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?

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.

6. (TCO 6) Assuming that the data are normally distributed with a mean of 45 and a standard deviation of 3.25, what is the z-score for a value of 40?

1.54

2.38

-1.36

-1.54

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 0.08. Choose the best interpretation of the hypothesis test.

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.

8. (TCO 8) A result of an entry level exam reveals that more than 22% of students fail that exam.

In a hypothesis test conducted at a level of significance of 2%, a P-value of 0.035 was obtained. Choose the best interpretation of the hypothesis test.

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.

9. (TCO 2) Having two types of cars called type A and type B. In observing the miles per gallon we found that both types make mean miles per gallon of 32. Car A has a standard deviation of 5 miles per gallon while car B has a standard deviation of 3 miles per gallon. Which of the two car types is more consistent in fuel consumption?

Type A car because it got more fuel consumption consistency.

Type B car because it got more fuel consumption consistency.

Either car type because their average fuel consumption is the same.

Neither car type because the given information is not enough to make a decision

10. (TCO 4) A jar contains balls of four different colors; red, blue, yellow and green. The total balls are 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 amount 5 15 25 60

Probability 45% 35% 15% 5%

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

11. (TCO 3) The grades of 22 students are listed below. Use the stem & leaf to determine the shape of the distribution. Choose the best answer.

4 | 7 5

5 | 1 7 5

6 | 5 6 7 8 9

7 | 1 6 7 8 8 9

8 | 2 4 7 6

9 | 4 7

The data is symmetric

The data is skewed to the right

The data is skewed to the left

The data is bimodal

12. (TCO 1) A researcher is interested in studying people's mean age in a certain region. If the population standard deviation is known to be 8 years and 1.5 year of error margin is allowed, find the minimum simple size the researcher needs to use, knowing that he is going to conduct his study using 95% confidence level.

Sample Size = 77

Sample Size = 25

Sample Size = 210

Sample Size = 110

13. (TCO 6) Horse race time is found to be normally distributed with a mean value of 18 minutes and a standard deviation of 4 minutes. Horses whose race time is in the top 6% 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?

26.6

11.8

24.2

20.3

14. (TCO 5) A class containing 15 students 5 of them are females. In how many ways can we select a group of 4 male students?

260

120

5040

210

15. (TCO 6) Research shows that the life time of Everlast automobile tires is normally distributed with a mean value of 65,000 miles and a standard deviation of 6,500 miles. What is the probability of having a tire that lasts more than 75,000 miles?

0.0618

1.54

0.9382

0.0606

16. (TCO 10) A research shows that employee salaries at company XYX, in thousands of dollars, are 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.

52.5

59.5

83.5

69.5

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