This function takes numTrials random numbers. Then it totals the number of random numbers that are less than prob. It returns that total. While similar to randInt(0,numTrials), this is much more likely to give a result close to numTrials*prob. :randBin(numTrials, prob, numSimulations) This creates a list of length numSimulations, each element the result of a randBin(numTrials, prob).