Hypothesis,critical value, test value....Please help me understand!

I need help please, I have a test coming up and I need to know how to do each step. PLEASE HELP.

An official with an elderly persons advocacy agency believes that the average monthly cost of medication used to control cholesterol has increased. A nathional study showed that the average monthly cost for the last 5 years for cholesterol control medication is $72.58 per month. The official selects a random sample of 50 elderly people who use medication to control cholesterol and finds the average cost to be $73.45 with a standard deviation of $2.25. What type of hypothesis test should be performed? At a 0.05 level of significance, what is the critical value for the hypothesis test? At a 0.05 level of significance, what is the test value? The official should conclude that the average cost has increased----true or false?

Please Help me understand