Question

Thompson and Thompson is a steel bolts manufacturing company. Their current steel bolts have a mean diameter of 149 millimeters, and a standard deviation of 8 millimeters. If a random sample of 50 steel bolts is selected, what is the probability that the sample mean would be less than 148.1 millimeters? Round your answer to four decimal places.

Answer 1

Solution :

Given that ,

mean = = 149

standard deviation = = 8

n = 50

= = 149

= / n = 8/ 50 = 1.1314

P( < 148.1) = P(( - ) / < (148.1-149) /1.1314 )

= P(z < -0.80 )

= 0.2119

Probability = 0.2119