Statistics Help, Please?

Question by R.: Statistics Help, Please?
1.
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 answered “No.” 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

2.
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 answered “Yes” and participated in a phone interview. 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

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
I’m not necessarily looking for the answers, but if someone could give me a “helpful” explanation on how to solve them, I would really appreciate it!!

Best answer:

Answer by M3
Survey Method NO YES TOTAL
Anonymous … 576 224 800
Personal ……. 600 200 800
Phone ………. 632 168 800
Total ……….. 1808 592 2400

Probability = favorable outcomes / sample space

1. P(no) =1808/2400
2. P(yes) =592/2400
3. P(anonymous | yes) = 224/592

btw, why did you make such a long q out of it when the data & prelim are common ?

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