Question

statistics

Answer 1

A construction company supplied 720 pylons in 1960 to construct elevated sections of highways. Using industry protocols it was determined that the service lifetime was normally distributed with a mean of 75 years and a population standard deviation of 12.5 years. Based on that information, the company suggested to proceed to the first replacements in 2015. It is now 2015 and upon inspection, 41 pylons from the original series have been found to be in need of replacement. Is this observation in accordance to the predictions from the normal statistics? Justify your answer.