Times for a surgical procedure are normally distributed. There are two methods. Method A has a mean of 28 Minutes and a standard deviation of 4 minutes, while B has a mean of 32 minutes and a standard deviation of 2 minutes.

Question

a)which procedure is preferred if the procedure must be completed within 28 minutes?
b) Thirty-eight minutes?
c) Thirty-six minutes?
Explain your reasoning?

Answer 1

Z = (score-mean)/SD

Compare the Z scores for both methods for each question.

a. Method A, Z = 0, Method B, Z = -2

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions/probabilities related to the Z scores.

Use a similar process for b and c.