00:01
Hey there, welcome to numerate.
00:03
So we have a recent poll here where americans unbeviewed the number of books they have read in the past year.
00:10
So we have a standard deviation of 16 .6 books.
00:14
We're trying to see the number of people survey to estimate the mean number of americans that read the previous year, which is within two books with 95 % confidence, 95%.
00:26
So our equation we're going to use here is the margin of error equation, since we're trying to, we're giving the margin error and we're trying to find n the sample size.
00:35
Marjority equals critical value of z times our standard deviation divided by the square root of n our sample size.
00:43
We rearrange our terms here and we will get an equals of z critical value times our standard deviation divided by a margin of error.
00:57
This entire fraction here will be squared to isolate n.
01:07
Alright, so let's check our values here.
01:11
So, divided by measure of error and then square looks correct.
01:15
So we can plug in our values here.
01:19
All right.
01:20
C critical value is first.
01:22
So we have a critical value through the confidence interval 95%.
01:26
So it will be 1 .96...