7. (TCO 8) The mean hours of Internet usage by adults in the US in claimed to be less than 25 hours per week. A hypothesis test is performed at a level of significance of 0.05 with a P-value of 0.11. 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.
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.

Answer:
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.




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. (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.

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



9. (TCO 2) A bank is going to choose between two systems A and B which helps in measuring customers waiting time. During the trial period, both systems showed an average waiting time of 10 minutes. Type A showed a standard deviation of 2 minutes while type B showed a standard deviation of 4 minutes. Which of the two systems the bank should choose? (Points : 6)
System A because in shows more consistency in measuring the average waiting time.
System B because in shows more consistency in measuring the average waiting time.
Either because their mean waiting time is the same in both systems.
Neither because the given information is not enough to make a decision

Answer:
System A because in shows more consistency in measuring the average waiting time.



10. (TCO 4) A jar contains balls of four different colors; red, blue, yellow and green. The total balls are divides as 40% red, 30% blue, 20% yellow, and 10% 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, $10, $20, $50 for red, blue, yellow and green ball respectively.


Winning amount
5
10
20
50
Probability
40%
30%
20%
10%

(Points : 6)
The expected winning amount is $12
The expected winning amount is $25
The expected winning amount is $14
The expected winning amount is $40

Answer:
The expected winning amount is $14



11. (TCO 3) The grades of 20 students are listed below. Use the stem & leaf to determine the shape of the distribution. Choose the best answer.
4 | 4
5 | 6 8
6 | 5 7 9
7 | 1 5 7 8 8 9
8 | 3 4 5 7 8 8 9
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

Answer:
The data is skewed to the left








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.

Answer:
The sample size needs to decrease


13. (TCO 6) Horse race time is found to be normally distributed with a mean value of 15 minutes and a standard deviation of 3 minutes. Horses whose race time is in the top 8% 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)
8.63
10.77
17.13
19.23

Answer: 19.23




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? (Points : 6)
260
120
5040
210

Answer: 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? (Points : 6)
0.0618
1.54
0.9382
0.0606

Answer: 0.0618