00:01
So for this question, we have a probability density function, f of t, that measures time between earthquakes.
00:10
For the first part of this question, we want to know what the probability that the time between two earthquakes is more than one year, but less than three.
00:20
So the probability that t is between 365 and 365 times three.
00:29
So let's click, check 35 .3 and 1090.
00:37
Okay, so our integral is going to be 365, 1090, 1095 of our pdf.
01:01
So this integral is going to come out to be negative e to the negative t over 365.
01:11
0 .1 evaluated from 1095 to 365.
01:26
And if we plug in our endpoints, we're going to get negative e to the negative 1095 over 365.
01:40
It's pretty unlikely that we'll be able to simplify this very much because we've got this decimal point one here.
01:47
So best bet, probably will be to just get a decimal approximation at the very end of all this.
01:53
But playing in our lower bound, we're going to get plus e to the negative 365 over 365 .0 .1.
02:09
So for the final answer, how i would write this is e to negative 365.
02:15
Whoops, let's make that a little neater.
02:19
365 over 365...