00:01
We have our standard normal distribution again with a mean of zero and a standard deviation of one.
00:05
And we want to find what the value is where the area to the left of it is point one.
00:13
So we want to find this number that has the area to the left of it being point one.
00:18
If i quick draw a picture, we want this area to be point one.
00:23
And so we know that that's a z value is negative.
00:26
And so i need to look up in my table for an area of 0 .1, and i'm looking, i'm looking, and i'm going to pick the one it's closest to.
00:35
And it's very close to an area of 0 .103.
00:40
That's the closest z value.
00:41
And that corresponds with a z value of negative 1 .28.
00:47
Now on part b, we want to find the value that has the area above it being 0 .8.
00:57
So again, if i draw a little picture, if you draw a little picture, you're much more likely...