A software developer makes 175 phone calls to its current customers.There is an 8 percent chance of reaching a given customer (instead of a busy signal,no answer,or answering machine).The normal approximation of the probability of reaching at least 20 customers is
A)0.022
B)0.007
C)0.063
D)0.937

Question

Quizplus · Accepted Answer

Using the normal approximation to the binomial distribution, the mean (μ) is 175 * 0.08 = 14 and the standard deviation (σ) is sqrt(175 * 0.08 * 0.92) ≈ 3.63. To find the probability of reaching at least 20 customers, we calculate the z-score for 19.5 (continuity correction) and find the probability from the standard normal distribution. The probability is approximately 0.063.

A Software Developer Makes 175 Phone Calls to Its Current