Q1.manufactures has a mean writing life of 40 pages with a SD of 2 pages. A purchasing agent selects a sample of 100 pens and them to test. The mean writing life for the same was 39 pages. Should the purchasing agent rejects the manufacturer’s claim?

Question

Q1.manufactures has a mean writing life of 40 pages with a SD of 2 pages. A purchasing agent selects a sample of 100 pens and them to test. The mean writing life for the same was 39 pages. Should the purchasing agent rejects the manufacturer’s claim?

Answer 1

Z = (score-mean)/SEm

SEm = SD/√n

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score.