Answer to Question #185349 in Statistics and Probability for Harry Shergill

Question

A machine produces ball bearings with diameter of 2.5 inches. It is known that the standard deviation of the ball bearings is 0.005 inches. A sample of 100 ball bearings is selected and average diameter is found to 0.498 inches. Determine the 99 per cent confidence interval.

Answer 1

99% confidence interval=$\bar x ±z_{\frac{\alpha}{2}}\frac {\sigma} {\sqrt n}$

$=0.498 ±2.58*\frac {0.005}{\sqrt {100}}$

=(0.4967,0.4993)