how do you do the following binomial distribution in excel...?

Question

there is a 5% probability
45 trials
what is the probabilty that it will happen less than 5 times.

i know binomdist. ....but that only tells you the probability of it happening an exact number of times. ...how do you do it for less than?

Answer 1

make a table, first column number of successes, second column is the formula using number of successes, .05 prob, and 45 trials, and make the last parameter false to get individual probabilities. make a 3rd column with the same formula (binomdist) but with the last parameter set to true to get cumulative probabilities. you should get about 0.927