statitic The hours of study and the final exam grades have this type of relationship

January 30, 2017

Question
Week 8 :

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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

2.(TCO 5) At a drive through window of a bank it’s found that 10 customers get served every 15 minutes. The bank’s manage is interested in finding a way to increase the number of customers that can be served. He thought that knowing the probability of serving 12 customers per 15 minutes could be helpful to him in the decision making process. 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

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? (Points : 6)

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 7 or 8 people get killed by shark attack this year? (Points : 6)

0.130141
0.202678
0.220221
0.797321

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.

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

2.30
1.60
3.10
-1.60

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. (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.

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.

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.

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%

(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

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

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.

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? (Points : 6)

26.6
11.8
24.2
20.3

14.(TCO 5) A class containing 25 students 12 of them are females. In how many ways can we select a group of 6 male students? (Points : 6)

1716
665280
1235520
924

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

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 7 years experience and 12 years education level. (Points : 6)

52.2
81.9
67.5
63.9

17.(TCO 9) Describe the correlation in this graph.

(Points : 6)

moderate positive
strong negative
moderate negative
strong positive

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Week 8 :

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

2.(TCO 11) A pizza restaurant manager claims that the average home delivery time for their pizza is no more than 25 minutes. A random sample of 49 home delivery pizzas was collected. The sample mean was found to be 26.5 minutes and the standard deviation was found to be 4 minutes. Is there evidence to reject the manager’s claim at alpha =.05? Perform an appropriate hypothesis test, showing the necessary calculations and/or explaining the process used to obtain the results. (Points : 20)

3.(TCO 5) At a jewelry store, the probability for a customer to make a purchase when entering the store is 35%. We asked 25 customers enter the store whether they made a purchase or not.
(a) Is this a binomial experiment? Explain how you know.
(b) Use the correct formula to find the probability that, out of 25 customers, exactly 10 of them make a purchase. Show your calculations or explain how you found the probability.
(Points : 20)

4.(TCO 6) The monthly utility bills are normally distributed with a mean value of \$130 and a standard deviation of \$15.
(a) Find the probability of having a utility bill between 100 and 150.
(b) Find the probability of having a utility bill less than \$90.
(c) Find the probability of having a utility bill more than \$160. (Points : 20)

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)

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)

7.(TCO 7) A company’s CEO wanted to estimate the percentage of defective product per shipment. In a sample containing 600 products, he found 45 defective products.

(a) Find a 99% 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)

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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