Question

A service department at a dealership calculates the average cost of service done at their department to be $1000 with a standard deviation of $200. The service department serviced80 vehicles today. What is the probability the average cost of service for the 80 vehicles is greater than $1100?A)0.31B)0.0000039C)0.999996D)Service costs are not normally distributed so we cannot compute the probability.

Answer 1

Step 1: Write out the probability function

`Z=(1100-1000)/(200)*\frac{1}{\sqrt[]{80}}=(100)/(200)*\sqrt[]{80}=0.5*8.944=4.472`

Given the value of the Z score to be 4.472, it cannot be found on the Z table.

Hence, the service costs are not normally distributed so we cannot compute the probability, Option D