CarMD reports that after two years of flat U.S. car repair costs, 2016 saw an increase. One of the most common problems that trigger the “check engine” light is the catalytic converter. Repairing the catalytic converter had a mean repair cost of $1,190 in 2016. 

Source: Digital in 2017 Global Overview, available at bit.ly/2qL9KVc.

Suppose a sample of 100 catalytic converter repairs completed in the last month was selected. The sample mean repair cost was $1,125 with the sample standard deviation of $250.

a. Is there evidence that the population mean repair cost is less than $1,190? (Use a 0.05 level of significance.)

b. Determine the p-value and interpret its meaning.