An experiment was devised to test whether the parameter of a sample from the density f(y)

An experiment was devised to test whether the parameter λ of a sample from the density f(y) = yeλy, y > 0 is equal to a believed value λ0 = 50. (a) Derive the most powerful test for the null hypothesis H0 : {λ = λ0} vs alternative hypothesis Ha : {λ = λa} for λa = 40. (b) Discuss whether this test is uniformly most powerful to test against a composite alternative Ha : {λ < λ0}.