I have a question with the following problem:

3. Assume we have n = 20 i.i.d. observations $1, $2, ..., xn from the exponential distribution with rate parameter A. We want to test H0:)\\58vs.I-Ia:)\\8. Develop a uniformly most powerful a: = 0.05 level test and derive the re jection region of this test. (Hint: When Xi, 1 S 2' S 71 independently follows an exponential distribution of rate A, then X := 23:] X; N Gamma(n, A), which has the density xWIeM, x 0. Use the quantile function qgamma(...,shape 2 ...,rate = ...,lower.tail = ..) in R to compute the cutoff value.)