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 serviced20 vehicles today. What is the probability the average cost of service for the 20 vehicles is between $900 and $1100?A)0.38B)0.97C)Sample size is too small, we do not know if service costs are normally distributed

Answer 1

From Central limit theorem, we must consider a sample based in at least 30 or more obwervations. That is, the sample is not significant to consider the service costs as normally distributed.