Approximate Binomial Probabilities Using the Normal Distribution
-A salesperson found that there was a 1% chance of a sale from her phone solicitations. Find the probability of getting 5 or more sales for 1000 telephone calls.
A) 0.9599
B) 0.0401
C) 0.8810
D) 0.0871

Question

Quizplus · Accepted Answer

The probability of getting 5 or more sales for 1000 telephone calls can be approximated using the normal distribution with mean 10 and standard deviation 3.16. The z-score for 5 is (5-10)/3.16 = -1.58. The probability of getting a z-score of -1.58 or less is 0.0564. Therefore, the probability of getting 5 or more sales is 1 - 0.0564 = 0.9436, which is closest to choice A.