Hypothesis testing

Posted by Kamal1 on May 29, 2009; 10:30pm
URL: http://discussion-forum.276.s1.nabble.com/Hypothesis-testing-tp2996383.html

In questions of the type:

Suppose a manufacturer makes a tool using an old process (mean defect rate 10%) and the standard deviation is 2. A new technology firm comes out with a process (mean sample defect rate 7%) with sample standard deviation of 1.8.

should we use the population standard deviation or the sample?