15. An electron is in an infinite square well of width a with the same potential form as in Problem 14, with a = 300 pm wide. What is the probability that one can detect the electron in the first excited state within an interval betwe x = 0.50a and x = 0.75a? (A) 0(B) 1/2 (C) 1/3(D) 1/4(E) 1/6.