00:01
We are looking at a normal distribution.
00:02
I'll start by drawing it.
00:05
The total area under this curve is 1, or 100%, and it's symmetric.
00:09
Its mean, mu, is 20.
00:11
Its standard deviation, sigma, is 1.
00:15
In part a we want the 14th percentile.
00:18
So that sum value down here, p14, defined as a point where 14 % of the time it's a lower incubation time, and the other 86 % of the time it's higher.
00:29
So this area is 0 .14.
00:31
To find this you need something with the normal distribution built in.
00:35
That could be software like excel or r.
00:37
I'm going to use my ti -84 calculator, but we're looking for an inverse normal function.
00:43
These have three inputs, area, mean, standard deviation.
00:47
They are reverse cumulative functions...