Question

A leading magazine (like Barron's) reported at one time that the average number of weeks an individual is unemployed is 15.5 weeks. Assume that for the population of all unemployed individuals the population mean length of unemployment is 15.5 weeks and that the population standard deviation is 9.1 weeks. Suppose you would like to select a random sample of 11 unemployed individuals for a follow-up study.

Find the probability that a single randomly selected value is between 9.7 and 12.2.
P(9.7 < X < 12.2)

Answer 1

Let , , n=11

Now ,

, From standard normal distribution table

Therefore , the probability that a single randomly selected value is between 9.7 and 12.2 is 0.1858