Question

Most sample surveys use random digit dialing equipment to call residential telephone numbers at random. the telephone polling firm zogby international reports that the probability that a call reaches a live person is 0.15. calls are independent. (a) a polling firm places 7 calls. what is the probability that none of them reaches a person?

Answer 1

The probability that none of the 7 calls reaches a person is approximately 0.1967.

Step-by-step explanation:

To find the probability that none of the 7 calls reaches a person, we need to calculate the probability that each individual call does not reach a person and then multiply those probabilities together.

The probability that a call reaches a live person is 0.15, so the probability that a call does not reach a live person is 1 - 0.15 = 0.85.

Therefore, the probability that none of the 7 calls reaches a person is 0.857 ≈ 0.1967.

Answer 2

The probability is 0.3206.

Since the probability of reaching a live person is 0.15, the probability of not reaching someone is 1-0.15=0.85.

The probabilities are independent, which means to find the probability of not reaching anyone on all calls we find (0.85)^7= 0.3206.