Opinion-polling organizations sometimes contact their respondents by sampling random telephone numbers.Assume that interviewers can now reach about 74% of Canadian households,while the percentage of those contacted who agree to cooperate with the survey is 32%.Each household,of course,is independent of the others.What is the probability of failing to contact a household or of contacting the household but not getting them to agree to the interview?
A)0.177
B)0.823
C)0.497
D)0.763
E)0.452

Question

Quizplus · Accepted Answer

The probability of failing to contact a household is 1 - 0.74 = 0.26.
The probability of contacting a household but not getting them to agree to the interview is (0.74)(1 - 0.32) = 0.5024.
The total probability of failing to get a response is the sum of these two probabilities:
0.26 + 0.5024 = 0.7624, which is closest to 0.763 (answer D).

Opinion-Polling Organizations Sometimes Contact Their Respondents by Sampling Random Telephone