A dialog for creating confidence intervals for one population mean,
given the confidence level and whether the population standard
deviation is known or unknown.
A dialog for creating confidence intervals for two population means,
given the confidence level, population standard deviations (if known),
and whether population variances are assumed equal.
Returns the cumulative binomial probability given n, k, and p,
the probability of less than k successes occurring in n trials
if a success occurs with probability p per trial