Statistics Review That I Need Help On!!!! Pleaseeeeee?
Question by Scott: Statistics review that I need help on!!!! Pleaseeeeee?
3.In a survey conducted by researchers at the University of Wisconsin, subjects were asked the question “Have you ever used cocaine?” in one of three methods, anonymous survey, personal interview, or phone survey. The contingency table below shows the results of this survey of 2400 students. Suppose one subject is randomly selected from this group. Find the probability that the subject participated in an anonymous interview given that the person answered “Yes.” Show this answer as a fraction. Do not attempt to reduce the fraction.
Survey Method NO YES TOTAL
Anonymous 576 224 800
Personal 600 200 800
Phone 632 168 800
Total 1808 592 2400
Answer_________________
5.In a survey conducted by researchers at the University of Wisconsin, subjects were asked the question “Have you ever used cocaine?” in one of three methods, anonymous survey, personal interview, or phone survey. The contingency table below shows the results of this survey of 2400 students. Suppose one subject is randomly selected from this group. The probability that the subject answered “No” and participated in a personal interview is 600/2400 or 0.25. This probability cannot be computed by multiplying P(No) times P(personal interview) that is by multiplying (1808/2400)*(800/2400) = 0.2511. Why is that true?
Survey Method NO YES TOTAL
Anonymous 576 224 800
Personal 600 200 800
Phone 632 168 800
Total 1808 592 2400
A.You would add the two probabilities.
B.The two events, “No” and “personal interview” are not mutually exclusive.
C.The two events, “No” and “personal interview” are not independent.
6.In a survey conducted by researchers at the University of Wisconsin, subjects were asked the question “Have you ever used cocaine?” in one of three methods, anonymous survey, personal interview, or phone survey. The contingency table below shows the results of this survey of 2400 students. Suppose one subject is randomly selected from this group. Answer each of the following.
Survey Method NO YES TOTAL
Anonymous 576 224 800
Personal 600 200 800
Phone 632 168 800
Total 1808 592 2400
1.0.247
2.0.28
3.0.25
4.0.21
5.No
6.Yes
7.0.093
8.0.083
9.0.07
Choose from (1-9) Use only once
A.What is the probability that the subject answered Yes?
B.What is the probability that the subject answered Yes given that it was an Anonymous
interview?
C.What is the probability that the subject answered Yes given that it was a Personal interview?
D.What is the probability that the subject answered Yes given that it was a Phone interview?
E.Based on these results, does it appear that the response is independent of type of interview?
Best answer:
Answer by Ron W
3) 592/2400
5) C.
6)
A: 1 (592/2400, as stated in #3)
B: 2 (224/800)
C: 3 (200/800)
D: 4 (168/800)
E: 5 (the probabilities are close, but for the large sample sizes I would expect closer)
Know better? Leave your own answer in the comments!