Statistics Homework - multiple choice

2. If you flip a coin three times, the possible outcomes are HHH, HHT, HTH, HTT, THH, THT, TTH, TTT. What is the probability of getting at most one head?

A. 4/9
B. 5/6
C. 7/8
D. 5/8 3. A study of two types of weed killers was done on two identical weed plots. One weed killer killed 15% more weeds than the other. This difference was significant at the 0.05 level. What does this mean? A. The improvement was due to the fact that there were more weeds in one study. B. The probability that the difference was due to chance alone is greater than 0.05. C. The probability that one weed killer performed better by chance alone is less than 0.05. D. There is not enough information to make any conclusion. 4. Jody checked the temperature 12 times on Monday, and the last digit of the temperature was odd six times more than it was even. On Tuesday, she checked it 18 times and the last digit was odd eight times more than it was even. Determine which series is closer to the 50/50 ratio of odd/even expected of such a series of temperature checks. A. The Monday series is closer because 1/6 is closer to 1/2 than is 1/8. B. The Monday series is closer because 6/12 is closer to 0.5 than is 8/18. C. The Tuesday series is closer because the 13/18 is closer to 0.5 than is 9/12. D. The series closest to the theoretical 50/50 cannot be determined without knowing the number of odds and evens in each series. 5. A study of 600 college students taking Statistics 101 revealed that 54 students received the grade of A. Typically 10% of the class gets an A. The difference between this group of students and the expected value is not significant at the 0.05 level. What does this mean in this case? A. The probability that the difference occurred due to chance is less than 0.05. B. The probability of getting an A is 10% and only 9% got an A in this study. The difference is less than 5% so it is not significant. C. There is not enough information to make any conclusion. D. The probability that the difference occurred due to chance is more than 0.05. 7. A committee of three people is to be formed. The three people will be selected from a list of five possible committee members. A simple random sample of three people is taken, without replacement, from the group of five people. Using the letters A, B, C, D, E to represent the five people, list the possible samples of size three and use your list to determine the probability that B is included in the sample. (Hint: There are 10 possible samples.) A. 0.6 B. 0.4 C. 0.7 D. 0.8

15. A bag contains 4 red marbles, 3 blue marbles, and 7 green marbles. If a marble is randomly selected from the bag, what is the probability that it is blue?

A. 2/11
B. 3/11
C. 5/14
D. 3/14

16. Suppose you have an extremely unfair die: The probability of a 6 is 3/8, and the probability of each other number is 1/8. If you toss the die 32 times, how many twos do you expect to see?

A. 2
B. 4
C. 3
D. 5

17. The data set represents the income levels of the members of a country club. Estimate the probability that a randomly selected member earns at least $98,000.

112,000 126,000 90,000 133,000 94,000 112,000 98,000 82,000 147,000 182,000 86,000 105,000

140,000 94,000 126,000 119,000 98,000 154,000 78,000 119,000

A. 0.4
B. 0.6
C. 0.66
D. 0.7

20. If you flip a coin three times, the possible outcomes are HHH, HHT, HTH, HTT, THH, THT, TTH, TTT. What is the probability that at least two heads occur consecutively?

A. 1/8
B. 3/8
C. 5/8
D. 6/8

21. Select the best fit line on the scatter diagram below.

A. A
B. B
C. C
D. None of the lines is the line of best fit

23. The scatter plot and best-fit line show the relation among the number of cars waiting by a school (y) and the amount of time after the end of classes (x) in arbitrary units. The correlation coefficient is -0.55. Use the line of best fit to predict the number of cars at time 4 after the end of classes.

A. 7.0
B. 6.0
C. 8.0
D. 3.5

24. Write possible coordinates for the single outlier such that it would no longer be an outlier.

A. (23, 18)
B. (20, 5)
C. (15, 15)
D. (12, 15)

25. A sample of nine students is selected from among the students taking a particular exam. The nine students were asked how much time they had spent studying for the exam and the responses (in hours) were as follows:

18, 7, 10, 13, 12, 16, 5, 20, 21

Estimate the mean study time of all students taking the exam. Round your answer to the nearest tenth of an hour if necessary.

A. 13 hours
B. 12.2 hours
C. 13.6 hours
D. It is not possible to estimate the population mean from this sample data

28. The scatter plot and best-fit line show the relation among the number of cars waiting by a school (y) and the amount of time after the end of classes (x) in arbitrary units. The correlation coefficient is -0.55. Determine the amount of variation in the number of cars not explained by the variation time after school.

A. 55%
B. 70%
C. 30%
D. 45%

29. Which graph has two groups of data, correlations within each group, but no correlation among all the data?

A.
B.
C.
D.

30. A sample of 64 statistics students at a small college had a mean mathematics ACT score of 28 with a standard deviation of 4. Estimate the mean mathematics ACT score for all statistics students at this college. Give the 95% confidence interval.

A. 28.0 to 30.0
B. 25.0 to 27.0
C. 29.0 to 31.0
D. 27.0 to 29.0

31. A population proportion is to be estimated. Estimate the minimum sample size needed to achieve a margin of error E = 0.01with a 95% degree of confidence.

A. 7,000
B. 8,000
C. 9,000
D. 10,000

32. A researcher wishes to estimate the proportion of college students who cheat on exams. A poll of 560 college students showed that 27% of them had, or intended to, cheat on examinations. Find the 95% confidence interval.

A. 0.2323 to 0.3075
B. 0.2325 to 0.3075
C. 0.2325 to 0.3185
D. 0.2323 to 0.3185

33. A researcher wishes to estimate the proportion of college students who cheat on exams. A poll of 490 college students showed that 33% of them had, or intended to, cheat on examinations. Find the margin of error for the 95% confidence interval.

A. 0.0432
B. 0.0434
C. 0.0425
D. 0.0427

34. The scatter plot and best-fit line show the relation between the price per item (y) and the availability of that item (x) in arbitrary units. The correlation coefficient is -0.95. Determine the amount of variation in pricing explained by the variation in availability.

A. 5%
B. 10%
C. 95%
D. 90%

36. Select the best estimate of the correlation coefficient for the data depicted in the scatter diagram.

A. -0.9
B. 0.1
C. 0.5
D. 0.9

38. Select the best estimate of the correlation coefficient for the data depicted in the scatter diagram.

A. 0.60
B. -0.97
C. 0.10
D. 0.60

39. Which line of the three shown in the scatter diagram below fits the data best?

A. A
B. B
C. C
D. All the lines are equally good

40. Monthly incomes of employees at a particular company have a mean of $5954. The distribution of sample means for samples of size 70 is normal with a mean of $5954 and a standard deviation of $259. Suppose you take a sample of size 70 employees from the company and find that their mean monthly income is $5747. How many standard deviations is the sample mean from the mean of the sampling distribution?

A. 0.8 standard deviations above the mean
B. 0.8 standard deviations below the mean
C. 7.3 standard deviations below the mean
D. 207 standard deviations below the mean