Is that 97 to 103 a 95% confidence interval for the mean?
[/SIZE][/FONT] Given a target mean of 100, a standard deviation of 1 when the process is in control, and the product is acceptable between the range of 97 to 103. A measurement outside this range is a failure.
If the process is in control, how many failures do you expect out of every 10,000 items produced?
O.K. Its been a while since I did a quality control course (assuming that is what you are doing?) but you could work backwards to find an initial n using the rule for a confidence interval and then determine if this sample size is big enough to map back to n= 10,000.