Show that under the null hypotheses of Section 16.3, T+ is a value of a random variable

Question:

Show that under the null hypotheses of Section 16.3, T+ is a value of a random variable whose is symmetrical about n(n + 1)/4 .
Distribution
The word "distribution" has several meanings in the financial world, most of them pertaining to the payment of assets from a fund, account, or individual security to an investor or beneficiary. Retirement account distributions are among the most...