Refer to the following frequency distribution for Questions 1, 2,3, and 4. 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.
Checkout Time (in minutes) Frequency
1. What percentage of the checkout times was less than 3 minutes?
2. Calculate the mean of this frequency distribution.
3. Calculate the standard deviation of this frequency distribution.
4. Assume that the smallest observation in this dataset is 1.2 minutes. Suppose this observation were incorrectly recorded as 0.12 instead of 1.2. Will the mean increase, decrease, or remain the same? Will the median increase, decrease or remain the same? Explain your answers.
5. What is the probability that the outcome of the second roll is an odd number, given that the first roll is greater than 4?
6. Are A and B independent? Why or why not?
7. Find the standard deviation.
8. Are any of these study times considered unusual in the sense of our textbook? Explain. Does this differ with your intuition? Explain.
9. Determine the five-number summary for this data.
10. Determine the mean temperature.
11. Determine the mode(s), if any.
12. What is the probability that a randomly selected senior is in at least one of the two classes ?
13. What is the probability that a randomly selected senior takes only one class?
14. How many elements are in the sample space of this experiment?
15. What is the probability that the three numbers drawn are all multiples of 3?
16. Determine the expected value of x.
17. Determine the standard deviation of x.
18. What is the number of trials (n), probability of successes (p) and probability of failures (q), respectively?
19. Find the probability that she returns at least 2 of the 10 serves from her opponent
20. Find the mean and standard deviation for the probability distribution.
21. What is the probability that a randomly selected pecan is between 10 and 12 feet tall?
22. Find the 90th percentile of the pecan tree height distribution.
23. If a random sample of 25 pecan trees is selected, what is the standard deviation of the sample mean?
24. A random sample of 225 SAT scores has a mean of 1500. Assume that SAT scores have a population standard deviation of 300. Construct a 95% confidence interval estimate of the mean SAT scores. Show all work. Just the answer, without supporting work, will receive no credit.
27. A certain researcher thinks that the proportion of women who say that the earth is getting warmer is greater than the proportion of men. The research conducted a survey, and found the following result :
(a) Identify the null hypothesis and the alternative hypothesis.
(b) Determine the test statistic. Show all work; writing the correct test statistic.
(c) Determine the critical value. Show all work; writing the correct critical value, without supporting work, will receive no credit.
(d) Is there sufficient evidence to support the claim that the proportion of women saying the earth is getting warmer is higher than the proportion of men saying the earth is getting warmer? Justify your conclusion.
28. Find an equation of the least squares regression line. Show all work; writing the correct equation, without supporting work, will receive no credit.
29. Based on the equation from # 28, what is the predicted value of y if x = 4? Show all work and justify your answer.
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