At a large department store, the average number of years of employment for a cashier is 5.7 with a standard deviation of 1.8 years, and the distribution is approximately normal.
If an employee is picked at random, what is the probability that the employee has worked
At the store for over 10 years?
A) 99.2%
B) 1.7%
C) 49.2%
D) 0.8%

Question

Quizplus · Accepted Answer

To find the probability that an employee has worked at the store for over 10 years, we use the Z-score formula: Z = (X - μ) / σ, where X is the value of interest (10 years), μ is the mean (5.7 years), and σ is the standard deviation (1.8 years). Plugging in the values gives Z = (10 - 5.7) / 1.8 = 2.39. Looking up 2.39 on a standard normal distribution table or using a calculator gives a right-tail probability of approximately 0.8%.

At a Large Department Store, the Average Number of Years