Every day, a random sample of 275 computer memory chips produced by a factory is tested to see if chips meet their minimum speed ratings for certain operations. If 2 of the chips failed the test on a day when 20,500 chips were made, which is the best estimate of the number of memory chips made that day are likely to meet the minimum speed ratings for those operations?

Question

mathmale · Answer

Ah, random sampling!  Ah, proportions (not means)!
So, x= 2, n = 275.  What's the sample proportion?
Once you have the sample proportion, all you have to do to answer this question is to multiply it by 20,500, the number of chips made on a certain day.