00:01
We need to find what is the minimal sample size that we should choose so that the estimate, in our case the sample mean, is within $3.
00:12
So it's the same as saying that we are going to have something like this.
00:16
So the difference between our estimate in this population, the true value in the population, is within $3.
00:26
So the way that we calculate this is using the formula to compute the sample size.
00:34
So the formula is given by z, a value z squared, the variance or the standard deviation squared, divided by the square of our margin of error.
00:51
So this value here defines the margin of error, which is $3.
00:57
The sigma here is given by the question, which is 42.
01:02
The only thing that we need to know is this z now.
01:06
So this z is related to the 96 % that we want to be confident.
01:13
So our 96 % confidence level.
01:16
So this z is coming from a standard normal distribution, in which we have, in this case, we have the z would be this value here...