Question

A manufacturer knows that their items have a normally distributed length, with a mean of 8.8 inches, and standard deviation of 0.7 inches.

If one item is chosen at random, what is the probability that it is less than 8.2 inches long?

Answer 1

0.1949

Explanation:

Given a normal distribution with;

Mean(m) = 8.8 inches

Standard deviation (sd) = 0.7 inches

If one item is chosen at random, what is the probability that it is less than 8.2 inches long?

Find the Z-score :

x = 8.2 inches

Z = (x - m) / sd

Zscore = (8.2 - 8.8) / 0.7

Zscore = - 0.6 / 0.7

Zscore = - 0.857 = - 0.86

P(Z < - 0.86) :

From z distribution table :

P(Z < - 0.86) = 0.1949

If one item is chosen at random, there is a probability of 0.1949 that it will be less than 8.2 inches long.