Let Z be the standard normal random variable. Determine the value of k such that
(a) P(Z ≤ k) = 0.90
(b) P(Z>k)=0.23
(c) P(X ≤ k) = 0.90, where X ∼ n(x; 11, 4)
(d) P(Z>k)=0.23, where X ∼ n(x; 11, 4)