Refer to Exercise 5. Additional pieces of yarn will be

Answer:

Step 1 of 1:

In this question, we are asked to improve the precision of the confidence interval while referring to exercise 5.

Which would increase the precision the most:

sampling 50 additional pieces of yarn from the old batch, 50 additional pieces from the new batch, or 25 additional pieces from each batch.

and

Here  and are variable.

Then 90% confidence interval for the difference  is,

Width of confidence interval =