At a local manufacturing plant, employees must complete new machine set ups within 30 minutes. New machine set-up times can be described by a normal model with a mean
Of 22 minutes and a standard deviation of four minutes. What percent of new machine
Set ups take more than 30 minutes?
A) 97.72%
B) 47.72%
C) 2.28%
D) 52.28%
E) none of the above

Question

Quizplus · Accepted Answer

We need to find the percentage of set-ups that take more than 30 minutes. To do this, we need to find the area to the right of 30 on the normal distribution curve. We can do this by standardizing the value of 30 using the formula z = (x - mu) / sigma, where x is the value we want to standardize, mu is the mean, and sigma is the standard deviation.

z = (30 - 22) / 4 = 2

Using a standard normal distribution table, we can find the area to the right of 2, which is 0.0228 or 2.28%. Therefore, the answer is C.

At a Local Manufacturing Plant, Employees Must Complete New Machine