Probability The function $f(x)=\frac{1}{\sqrt{2 \pi}} e^{-x^{2} / 2},$ encountered in probability theory, is called the standard normal density function. Determine where this function is increasing and decreasing, find all local maxima and local minima, find all inflection points, and determine the intervals where $f$ is concave up and concave down. Then graph the function.