According to the Bureau of Labor Statistics it takes an average of 22 weeks for someone over 55 to find a new job. Assume that the probability distribution is normal and that the standard deviation is two weeks. What is the probability that eight workers over the age of 55 take an average of more than 20 weeks to find a job?
A) 0.8977
B) 0.6777
C) 0.7788
D) 0.9977

Question

Quizplus · Accepted Answer

The standard error for the sample mean is 2/sqrt(8) = 0.7071. The z-score for 20 weeks is (20-22)/0.7071 = -2.83. The probability of a z-score greater than -2.83 is approximately 0.9977.

According to the Bureau of Labor Statistics It Takes an Average