2.1.992 Part 1 Section 22.214.171.124, NORMINV
a. The standard states that the function uses an iterative search technique.
Office does not require an iterative search technique to be used.
b. The standard states if probability < 0 or probability > 1, #NUM! is returned.
Office returns #NUM! if probability is <= 0 or if probability is >= 1.