00:01
Hi, in this question we want to find the z -scores that bound the middle at 98 % of the area under the standard normal curve.
00:09
So the standard normal curve, which you're probably familiar with, already looks something like this.
00:18
Best to do something decent.
00:24
And so we want to go a certain number of deviations so that this middle region, right, is 98 % of the total area under the curve.
00:39
So the way that we do that is we use the z -score table, which tells us how much area is bounded to the left of a z -score, and then we look for this number here, and it'll tell us the area including this, uh, let me do a different color, including this part, which we want to actually ignore.
01:01
But if we look for a z -score corresponding to 99%, right, so not 98, 99 % of the area, then that'll include this part, which is the 1 % that we don't care about...