Posted by **Jamey** on Sunday, January 13, 2008 at 4:49pm.

The producer of HB pencils has 720 pencils randomly chosen from each day's productions. A defect rate of 15% is acceptable.

a) Assuming that 15% of all manufactured pencils are defective, what is the probability of finding at least 80 percent defective pencials in this sample?

b) If 120 pencils are found to be defective in today's sample, is it likely that the manufacturing process may need improvements? Explain....