A manufacturing firm produces a product that has a ceramic coating. The coating is baked on to the product, and the baking process is known to produce 15% defective items (for example, cracked or chipped finishes). Every hour, 20 products from the thousands that are baked hourly are sampled from the ceramic-coating process and inspected.
a. What is the probability that 5 defective items will be found in the next sample of 20?
b. On average, how many defective items would be expected to occur in each sample of 20?
c. How likely is it that 15 or more nondefective (good) items would occur in a sample due to chance alone?