00:01
In this question, we are looking at a poisson distribution.
00:06
The formula that we're going to use, the poisson formula, is the probability of exactly x occurrences, is lambda to the power of x, e to the minus lambda, over x factorial.
00:17
So this is for a given rate of independent occurrences, and the rate lambda is 0 .534.
00:27
We want the probability of having fewer than three failures.
00:31
So x is below 3.
00:34
Now, before i go ahead, i need to check that the times spans are the same.
00:37
So the rate we're given is per year.
00:39
We're looking at a year, so that matches up.
00:42
We can use this value of lambda.
00:43
We don't have to adjust it.
00:45
So if it's less than 3, it could be 0, it could be 1, it could be 2...