> it appears you didn't use the binomial distribution formulas for this You would use binomial distribution formulas if the problem was more complex. Say, if y

> it appears you didn't use the binomial distribution formulas for this You would use binomial distribution formulas if the problem was more complex. Say, if you cared about how many times you get covid infected, or how many times your winning ticket is drawn. The problem here is a special, simpler case. > Is there a name I could google for the formulas you used ? Any intro to probabilities book will start with such problems. If you really want to google something, the basic assumption here is that the events are "independents". You can find examples here: https://en.wikipedia.org/wiki/Independence_(probability_theory)#Examples https://en.wikipedia.org/wiki/Independence_(probability_theo...