Answer all 25 questions. Make sure your answers are as complete as possible.
Show all of your work and reasoning. In particular, when there arecalculations involved, you must show how you come up with your answerswith critical work and/or necessary tables. Answers that come straight fromprograms or software packages will not be accepted.
Record your answers and work on the separate answer sheet provided.
You must include the Honor Pledge on the title page of your submitted finalexam. Exams submitted without the Honor Pledge will not be accepted.
1. True or False. Justify for full credit.
(a) The normal distribution curve is always symmetric to its mean.
(b) If the variance from a data set is zero, then all the observations in this data set areidentical.(c) .ofcomplementtheis where,1)AND(AAAAPcc(d) In a hypothesis testing, if the p-value is less than the significance level a, we do nothave sufficient evidence to reject the null hypothesis.(e) The volume of milk in a jug of milk is 128 oz. The value 128 is from a discrete dataset.
Refer to the following frequency distribution for Questions 2, 3, 4, and 5. Show all work. Just theanswer, without supporting work, will receive no credit.
A random sample of 25 customers was chosen in UMUC MiniMart between 3:00 and 4:00PM on a Friday afternoon. The frequency distribution below shows the distribution forcheckout time (in minutes).
Checkout Time (in minutes)
Frequency
Relative Frequency
1.0 - 1.9
2
2.0 - 2.9
8
3.0 - 3.9
4.0 - 5.9
5
2. Complete the frequency table with frequency and relative frequency.
3. What percentage of the checkout times was less than 3 minutes?
4. In what class interval must the median lie? Explain your answer.
5. Assume that the largest observation in this dataset is 5.8. Suppose this observation wereincorrectly recorded as 8.5 instead of 5.8. Will the mean increase, decrease, or remainthe same? Will the median increase, decrease or remain the same? Why?
6. A random sample of STAT200 weekly study times in hours is as follows:
2 15 15 18 30
Find the sample standard deviation. (Round the answer to two decimal places. Show all work.Just the answer, without supporting work, will receive no credit.)
image501Refer to the following information for Questions 7, 8, and 9. Show all work. Just the answer,without supporting work, will receive no credit.
A fair coin is tossed 4 times.
7. How many outcomes are there in the sample space?
8. What is the probability that the third toss is heads, given that the first toss is heads?
9. Let A be the event that the first toss is heads, and B be the event that the third toss is heads. Are Aand B independent? Why or why not?
Refer to the following situation for Questions 10, 11, and 12.
The boxplots below show the real estate values of single family homes in two neighboringcities, in thousands of dollars.
For each question, give your answer as one of the following: (a) Tinytown; (b) BigBurg; (c) Bothcities have the same value requested; (d) It is impossible to tell using only the given information.Then explain your answer in each case.
10. Which city has greater variability in real estate values?
11. Which city has the greater percentage of households with values $85,000 and over?
12. Which city has a greater percentage of homes with real estate values between $55,000and $85,000?
Refer to the following information for Questions 13 and 14. Show all work. Just the answer,without supporting work, will receive no credit.
There are 1000 juniors in a college. Among the 1000 juniors, 200 students are takingSTAT200, and 100 students are taking PSYC300. There are 50 students taking bothcourses.
image501
13. What is the probability that a randomly selected junior is taking at least one of these twocourses?
14. What is the probability that a randomly selected junior is taking PSYC300, given thathe/she is taking STAT200?15. UMUC Stat Club is sending a delegate of 2 members to attend the 20
15 Joint Statistical Meetingin Seattle. There are 10 qualified candidates. How many different ways can the delegate beselected?
16. Imagine you are in a game show. There are 4 prizes hidden on a game board with 10spaces. One prize is worth $100, another is worth $50, and two are worth $10. You have to pay$20 to the host if your choice is not correct. Let the random variable x be the winning. Show allwork. Just the answer, without supporting work, will receive no credit.
(a) What is your expected winning in this game?
(b) Determine the standard deviation of x. (Round the answer to two decimal places)
17. Mimi just started her tennis class three weeks ago. On average, she is able to return 20%of her opponent's serves. Assume her opponent serves 8 times. Show all work. Just the answer,without supporting work, will receive no credit.
(a) Let X be the number of returns that Mimi gets. As we know, the distribution of X is a binomialprobability distribution. What is the number of trials (n), probability of successes (p) andprobability of failures (q), respectively?
(b) Find the probability that that she returns at least 1 of the 8 serves from her opponent.
(c) How many serves can she expect to return?Refer to the following information for Questions 18, 19, and 20. Show all work. Just the answer,without supporting work, will receive no credit.
The IQ scores are normally distributed with a mean of 100 and a standard deviation of 15.
18. What is the probability that a randomly selected person has an IQ between 85 and 115?
19. Find the 90th percentile of the IQ distribution.
20. If a random sample of 100 people is selected, what is the standard deviation of the sample mean?
21. A random sample of 100 light bulbs has a mean lifetime of 3000 hours. Assume that thepopulation standard deviation of the lifetime is 500 hours. Construct a 95% confidence interval
image501estimate of the mean lifetime. Show all work. Just the answer, without supporting work, willreceive no credit. (10 pts)
22. Consider the hypothesis test given by
5.0:5.0:10pHpH
In a random sample of 225 subjects, the sample proportion is found to be. 51.0ˆp
(a) Determine the test statistic. Show all work; writing the correct test statistic, withoutsupporting work, will receive no credit.(b) Determine the p-value for this test. Show all work; writing the correct P-value,without supporting work, will receive no credit.(c) Is there sufficient evidence to justify the rejection of at the level?Explain. 0H0.01
23. A new prep class was designed to improve AP statistics test scores. Five students wereselected at random. The numbers of correct answers on two practice exams wererecorded; one before the class and one after. The data recorded in the table below. Wewant to test if the numbers of correct answers, on average, are higher after the class.
Number of Correct Answers
Subject
Before the class
After the class
1
12
14
2
15
18
3
9
11
4
12
10
5
12
12
Is there evidence to suggest that the mean number of correct answers after the classexceeds the mean number of correct answers before the class?
Assume we want to use a 0.01 significance level to test the claim.
(a) Identify the null hypothesis and the alternative hypothesis.(b) Determine the test statistic. Show all work; writing the correct test statistic, withoutsupporting work, will receive no credit.(c) Determine the p-value. Show all work; writing the correct critical value, withoutsupporting work, will receive no credit.(d) Is there sufficient evidence to support the claim that the mean number of correctanswers after the class exceeds the mean number of correct answers before the class?Justify your conclusion.
24. A random sample of 4 professional athletes produced the following data where x is thenumber of endorsements the player has and y is the amount of money made (in millions ofdollars).
x
0
1
3
5
y
3
2
3
8
(a) Find an equation of the least squares regression line. Show all work; writing the correctequation, without supporting work, will receive no credit.
(b) Based on the equation from part (a), what is the predicted value of y if x = 4? Show allwork and justify your answer.
25. Randomly selected nonfatal occupational injuries and illnesses are categorized accordingto the day of the week that they first occurred, and the results are listed below. Use a 0.05significance level to test the claim that such injuries and illnesses occur with equalfrequency on the different days of the week. Show all work and justify your answer.
Day
Mon
Tue
Wed
Thu
Fri
Number
22
22
20
19
17
(a) Identify the null hypothesis and the alternative hypothesis.(b) Determine the test statistic. Show all work; writing the correct test statistic, withoutsupporting work, will receive no credit.(c) Determine the p-value. Show all work; writing the correct critical value, withoutsupporting work, will receive no credit.(d) Is there sufficient evidence to support the claim that such injuries and illnesses occurwith equal frequency on the different days of the week? Justify your answer.