00:01
For this problem, in part a, we're looking for the probability of x less than or equal to 1.
00:06
Now, i think that you're correct there.
00:08
So one second here.
00:09
Oh, actually, just in case other people are looking up this question, i'll go through all of this.
00:14
So probability of x less than or equal to 1 is the same as the probability of z, less than or equal to the z score corresponding to 1.
00:21
So we find that z score by taking 1 minus the mean, mu, divided by the standard deviation, sigma.
00:27
Oh, leftovers from a previous problem there.
00:29
So we find that z score then, by doing 1 minus, the mean here is 19, and we know that the standard deviation is 10.
00:36
So this is the same as the proportion of the standard normal distribution to the left of negative 1 .8.
00:41
You can find that by going to a cumulative distribution table here.
00:44
Go to the negative 1 .8 row, the 0 .0 column.
00:48
We find that, yeah, it's 0 .0359...