Answer:
A sample size of at least 737 specimens is required.
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:
 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
, so 
Now, find the width M as such

In which  is the standard deviation of the population and n is the size of the sample.
 is the standard deviation of the population and n is the size of the sample.
In this problem, we have that:

So:





A sample size of at least 737 specimens is required.