Question

Thompson and thompson is a steel bolts manufacturing company. their current steel bolts have a mean diameter of 140140 millimeters, and a standard deviation of 88 millimeters. if a random sample of 4949 steel bolts is selected, what is the probability that the sample mean would be greater than 141.4141.4 millimeters? round your answer to four decimal places.

Answer 1

To solve this, we need to use the z test. The formula for z score is:

z = (x – u) / s

where x is sample value = 141.4 mm and above, u is mean value = 140 mm, s is standard dev = 8 mm.

 

z = (141.4 – 140) / 8

z = 0.175

 

From the standard probability tables, the p value at z = 0.175 using right tailed test is:

P = 0.4306