89. Let I1,..., In be independent random variables, each of which is equally likely to be either 0 or 1. A well-known nonparametric statistical test (called the signed rank test) is concerned with determining Pn(k) defined by Pn(k) = P

⎧

⎨

⎩

n j=1 j Ij k

⎫

⎬

⎭