00:01
So for this question, actually we have a binomial random variable with total number being 40 and the probability for each people who does not show up for the flight is 0 .0995.
00:15
So let's say this is n, this is p here.
00:18
And then we want to find a set of probabilities the first way.
00:22
Before we do that, we can write down the probability mass function for the binomial distribution when x is equal to k, we choose k from n times p to the power of k, and then times 1 minus p to the power of n minus k.
00:39
So k here could be equal to n, k could be from 0, 1, to any integers until 40.
00:49
And then for the first probability, we want to find the probability that fewer than 5, x is smaller than 5.
00:59
And then this is equal to the probability that x is equal to 0, 1, 2, 3, and 4, fewer than 5.
01:08
So we need to put each of the 5 values into the probability mass function and find the probability for each, and then we sum up all these...