Question

Assume that the salaries of elementary school teachers in the United States are normally distributed with a mean of 32,000 and a standard deviation of 3,000. If 100 teachers are randomly selected, find the probability that their mean salary is less than 32,000.

Answer 1

Solution :

Given that ,

mean = = 32000

standard deviation = = 3000

n = 100

= 32000

= / n = 3000 / 100 = 300

P( < 32000) = P(( - ) / < (32000 - 32000) / 300)

= P(z < 0)

= 0.5