Suppose the contact rate for a phone survey is 78% and that 22% of people will participate in that survey. Assume that agreeing or not agreeing to participate is independent of whether the house is contacted.

a) What is the probability that the next house will be contacted and refuse to cooperate?

b) What is the probability of failing to contact a house, or making contact and not getting them to agree to the interview?

Remember that, for independent events, the probability that both occurr is the product of the individual probabilities.

a) Probability of being contacted: 78% = 0.78

Probaility of refusing: 1 - 22% = 1 - 0.22 = 0.78

Combined probability: 0.78*0.78 = 0.6084

b) The probability of failing to contact or making contact and not geeting them to agree 1 - the probability of contacting and getting them to agree.

The probabilityof contacting and getting them to agree is 0.78*0.22 = 0.1716

The the answer to this question is 1 - 0.1716 = 0.8284