Question 378060
Well...this appears to be a pure statistics problem; even though I have never taken a statistics class, one possible way to solve it is to construct a definite integral with bounds from negative infinity to z. If there is a simple expression for the integral of the normal curve given by {{{(1/sqrt(2pi))e^((-x^2)/2)}}} (this is the expression I have seen for the normal distribution) then z can be easily found, using basic theorems from calculus.