posterior distribution

A child is given an IQ test. Assume the test result X is N(q,100) (std.dev=10) where q is the true IQ of the child. Also assume that the in the population as a whole q is distributed N(100,225) (=prior).
a) Find the marginal for X (use results in class)
b) If the child scores 115, find the posterior distribution of q and the maximum likelyhood estimate of q
c) Find a 95% confidence interval for q using posterior in b)