Question

a previous analysis of paper boxes showed that the standard deviation of their lengths is 15 millimeters. A packers wishes to find the 95% confidense interval for the average length of a box. How many boxes do he need to measure to be accurate within 1 millimeters

Answer 1

864.36 boxes

Explanation:

In the question above, we are given the following values,

Confidence interval 95%

Since we know the confidence interval, we can find the score.

Z score = 1.96

σ , Standards deviation = 15mm

Margin of error = 1 mm

The formula to use to solve the above question is given as:

No of boxes =[ (z score × standard deviation)/ margin of error]²

No of boxes = [(1.96 × 15)/1]²

= 864.36 boxes

Based on the options above, we can round it up to 97 boxes.