00:01
So in part a, we want to find the probability that a randomly selected time interval between the eruptions is longer than 95 minutes.
00:09
So longer than 95 minutes, so we have z is equal to 95 minus 85 over our standard deviation, which is 21 .25.
00:20
And we get an answer of 0 .47.
00:22
So we get our table and we find the probability that z is greater than 0 .47, which gives us 0 .3192 or 31 .92%.
00:35
In part b, we want to find the probability of 20 time intervals.
00:42
So that's z is equal to 95 minus 85 over.
00:47
We are dividing that value, this 21 .25 divided by square root of 20, and that gives us 4 .75.
01:07
All right, and this gives us an answer of 2 .105.
01:12
So our probability of z being greater than 2 .105 from the table is 0 .0188.
01:22
Now it's the probability that a random sample of 30 time intervals...