An engineering firm is evaluating their back charges, and from this they claim that their average back charge?

An engineering firm is evaluating their back charges, and from this they claim that their average back charge is $1800. They randomly select 40 customers, and calculate the sample mean back charge to be $1925. If the standard deviation of back charges is $600, and alpha = 0.05, test the claim of the engineering firm. Perform an appropriate hypothesis test, showing the necessary calculations and/or explaining the process used to obtain the results.