Need help with this stats problem

A certain type of stainless steel powder is supposed to have a mean particle diameter of ,4! =15 ,am. A random sample of 87 particles had a mean diameter of 15.2 ,am, with a standard deviation of 1.8 ,am. A test is made to see whether the mean particle diameter is 15 ,am or not. (a) (1 pt) State the hypothesis test, that is, the null hypothesis and the alternative hypothesis. (b) (2 pts) Find the Pvalue. (c) (1 pt) Set the significance level as 0.05. Do you believe it is plausible that the mean diameter is 15 ,am, or are you convinced that it differs from 15 ,am? What is your conclusion? Explain your reasoning