00:01
We are looking at a normal distribution.
00:03
I'll start by drawing it.
00:11
So the total area under this curve is 1 or 100 % and it is symmetric.
00:19
Half of the area is below the mean, half above the mean.
00:23
The mean is 24 .6 miles per gallon with a standard deviation of 3 .2 miles per gallon.
00:31
So in part a, we're told that if you mark 26 on this curve, so that's above the mean, the area to its right, so this area here, is 0 .3309.
00:46
How can we interpret that? so there are two interpretations of this area.
00:51
One is for probability, one is for proportion, and those tend to be synonymous when we're looking at probability curves.
01:04
So the first interpretation is that the probability of the miles per gallon, so miles per gallon for each fill up, will exceed 26.
01:18
So probability, miles per gallon, exceeds 26 on a random fill up.
01:31
So it's just a single observation from this distribution...