00:01
We're looking at bone density, and the test scores are normally distributed.
00:06
So we have some pictures of a normal distribution here.
00:10
We need to know which one accurately represents this question.
00:14
So there's a mean, mu, of zero, and a standard deviation, sigma of one.
00:21
And we're looking for the probability of a test score greater than minus 1 .51.
00:28
So we have minus 1 .51.
00:30
Greater just means anything to the right of it.
00:35
Any of this.
00:36
So the answer here is going to be c.
00:38
D shows you the probability of less than minus 1 .51.
00:43
A shows you the probability of less than positive 1 .51.
00:46
B shows you the probability between minus 1 .51 and 1 .51.
00:52
So how do we actually find this probability? well, we're using a normal distribution.
00:57
Usually we would have to convert into a z score, which is a measure of how many standard deviations away from a mean a value is.
01:06
So you take your data point, subtract the mean, divide by standard deviation...