00:01
It's probably doing with an exponential distribution.
00:03
I'm going to make use of an exponential calculator in order to do this.
00:07
It can be done by hand using calculus.
00:10
But if you have access to an online exponential calculator, it just makes things a whole lot easier.
00:17
I'm using stat crunch here, but others are available as well.
00:21
So let me go to stat crunch.
00:23
And here's my exponential calculator.
00:26
Now, i'm told that we have a mean of 10 minutes.
00:31
So let's make this mean 10 minutes.
00:35
First one, we want to find the probability that lasts less than 20 minutes.
00:38
Let's make that less than 20 minutes...