00:01
Now on this problem, we are told that six small aircraft arrive at an airport per hour.
00:08
Now, we're told that this is according to a posan process of lambda 6.
00:13
So the probability of x is e to the negative 6 times 6 to the x over x factorial, according to the posan distribution formula.
00:23
On a, we want the probability that exactly four small aircraft arrived during a one hour period.
00:29
And so on a, we want the probability of 4, which is e to the negative 6 times.
00:36
Times 6 to the 4 over 4 factorial.
00:39
All we did was plug in 4 for x.
00:46
And then we're just going to evaluate this.
00:49
And when we do, this is 0 .139.
00:59
On b, we want to find the probability that at least 4 arrive.
01:06
And so the probability that x is greater than or equal to 4 is equal to 1 minus the probability that x is less than or equal to 3...