Answer:
He will need 4 newborns in the sample to be 95% confident.
Step-by-step explanation:
We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of .
So it is z with a pvalue of , so
Now, find the margin of error M as such
In which is the standard deviation of the population and n is the length of the sample.
So:
He will need 4 newborns in the sample to be 95% confident.