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
Is the answer 1808/2400?
Sorry for the 2nd post...please omit...
Yes.
To find the probability that the subject answered "No" when randomly selected from this group, we need to sum up the number of "No" answers across the three survey methods and divide it by the total number of students.
In this case, we sum up the number of "No" answers from each row:
Anonymous: 576
Personal: 600
Phone: 632
Adding these values together, we get: 576 + 600 + 632 = 1808
Dividing this by the total number of students (2400), we get the probability:
1808 / 2400
Therefore, the answer is indeed 1808/2400.