I am stuck on this problem. How can I resolve this?

I have tried myself and not working. Please help.

Suppose that when a transistor of a certain type is subjected to an accelerated life test, the lifetime X (in weeks) has a gamma distribution with mean 24 weeks and standard deviation 12 weeks. a) What is the probability that a transistor will last between 18 and 30 weeks? (Give decimal answer to three places past decimal.) 0.10111 Submit Answer Incorrect. Tries 1/2 Previous Tries b) What is the probability that a transistor will last at most 24 weeks? (Give decimal answer to two places past decimal.) 0.53 Submit Answer Incorrect. Tries 1/2 Previous Tries c) Use the answer in b) to compare the median with the mean: The median of the lifetime distribution less than 24 The median of the lifetime distribution equals 24 No enough information to compare them The median of the lifetime distribution lager than 24 Submit Answer Tries 0/1 d) What is the 99.5th percentile of the lifetime distribution? (Give a whole number answer.) Submit Answer Tries 0/2 e) Suppose the test will actually be terminated after t weeks. What value of t is such that only 1% of all transistors would still be operating at termination? (Give a whole number answer.) Submit Answer Tries 0/2