00:01
Let me take notes what's given here.
00:03
So the population mean denoted by mu, this is 100.
00:07
And the standard deviation is also given here for the population, which is 15 here.
00:11
So we can define the random variable x.
00:14
This is normally distributed, 100 and 15.
00:17
So what do we have to find? in part a, we have to find the probability of random variable x, which is between 90 and 110.
00:26
To get this one, i'm going to use the graph and display calculator application, normalcdf.
00:30
So the lower boundary is 90, upper boundary is 110.
00:34
So the mean is 100 and the standard deviation is 15 here.
00:37
To get the normal cdf, press 2nd, and then the variance, the normal cdf, lower boundary, which is 90, upper boundary is 110, and the mean is 100, and the standard deviation, which is 15.
00:50
So the probability would be 0 .4950.
00:54
This is the probability.
00:57
And the mean here, which is, this is less than 90.
01:00
So the probability of x, which is less than 90.
01:03
Again, i'm going to use the normal cdf here.
01:06
So there is no lower boundary, but a very small number...