STAT200 FINAL EXAM

STAT200 FINAL EXAM

18PAGES. All Questions and Answers

1. True or False. Justify for full credit.

(a) If the variance of a data set is zero, then all the observations in this data set are zero.

(b) If P(A) = 0.4 , P(B) = 0.5, and A and B are disjoint, then P(AAND B) = 0.9.

(c) Assume X follows a continuous distribution which is symmetric about 0. If , then .

(d) A 95% confidence interval is wider than a 90% confidence interval of the same parameter.

(e) In a right-tailed test, the value of the test statistic is 1.5. If we know the test statistic follows a Student’s t-distribution with P(T < 1.5) = 0.96, then we fail to reject the null hypothesis at 0.05 level of significance .

Refer to the following frequency distribution for Questions 2, 3, 4, and 5. Show all work. Just the answer, without supporting work, will receive no credit.

The frequency distribution below shows the distribution for checkout time (in minutes) in UMUC MiniMart between 3:00 and 4:00 PM on a Friday afternoon.

2. Complete the frequency table with frequency and relative frequency. Express the relative frequency to two decimal places.

3. What percentage of the checkout times was at least 3 minutes?

4. In what class interval must the median lie? Explain your answer.

5. Does this distribution have positive skew or negative skew? Why?

Refer to the following information for Questions 6 and 7. Show all work. Just the answer, without supporting work, will receive no credit.

Consider selecting one card at a time from a 52-card deck. (Note: There are 4 aces in a deck of cards)

1. If the card selection is without replacement, what is the probability that the first card is an ace and the second card is also an ace? (Express the answer in simplest fraction form)
   (5 pts)

2. If the card selection is with replacement, what is the probability that the first card is an ace and the second card is also an ace? (Express the answer in simplest fraction form)

3. Refer to the following situation for Questions 8, 9, and 10.

   The five-number summary below shows the grade distribution of two STAT 200 quizzes for a sample of 500 students.

   For each question, give your answer as one of the following: (a) Quiz 1; (b) Quiz 2; (c) Both quizzes have the same value requested; (d) It is impossible to tell using only the given information. Then explain your answer in each case.

   8. Which quiz has less interquartile range in grade distribution?