00:01
Okay, let's make a bell curve that represents this standard deviation for number one.
00:07
So the mean is 78, so that's right in the middle, and standard deviation is 5.
00:15
So if i count by fives, 78 plus 5 is 83, 83 plus 5 is 88, 78 minus 5 is 73, minus 5 again is 68.
00:30
So which list is ordered from the most likely to the least likely? so your most likely scores are in this area, and in a normal distribution, 68 percent of your scores fall in this area.
00:51
So chance choice a is 78, 81, 74, 85, and 42.
01:02
So it needs to be ordered from the most likely to the least likely.
01:07
So 78 is definitely the most likely, 81 is three points away.
01:17
The further i get away from the mean, the less likely it is.
01:21
So it doesn't matter if it's above or below.
01:24
So let's just say this is three points away, 74 is four points away, 85 is seven points away, and 42 is a whole bunch of points away.
01:42
So this one definitely works.
01:46
Let's look at b, c, and d, and see if we can exclude any of them.
01:57
So 81 is three away, 74 is four away, 78 is the mean.
02:03
So it's definitely not b.
02:08
C starts with the one that's furthest away, so that's definitely not it.
02:14
And d, we've got 74, 78, 81, 42, and 82.
02:23
So again, 74 is four away from the mean, 78 is the mean.
02:28
So it's not d, a is your best choice.
02:32
So again, just looking at the distance from the mean.
02:37
Okay, let's look at another one.
02:39
So now we're doing a mean of, this is question two, 130, and a standard deviation of two.
02:54
So again, we're going from least likely to, well, this one's the opposite order.
03:08
This one's least likely to most likely.
03:12
So a is 134, 131, 130, 128, 120.
03:22
So i know right away that this one can't be the right answer because that 130 is sitting in the middle.
03:28
134 is four away, 131 is one away, 130 is zero away, 128 is two away.
03:38
Those are not in any kind of order.
03:41
So it's not a...