00:01
Let's have a look on the question.
00:01
So, here a doctor wants to estimate the cholesterol level of 20 to 29 year old females.
00:06
Now, we need to find out the value of n that is the sample size which says how many subjects are needed to estimate mean hdl cholesterol within 5 points with 95 % confidence.
00:17
So, which means we have confidence level is equal to 95 % assuming s is equal to 18 .7 based on the earlier studies.
00:28
So, from the statement we can see that we have standard deviation then we have the margin of error that is 5 and the confidence interval.
00:36
So, we can write alpha will be equal to 1 minus confidence interval which is equal to 0 .05.
00:43
Now, here we need to find out the value of n.
00:47
So, the formula of margin of error e is given by sigma divided by under root of n multiplied by z of alpha divided by 2.
00:56
So, here if we reverse the formula this will be equal to under root of n is equal to sigma multiplied by z of alpha divided by 2 divided by e...