Решение задачи N490 теория вероятностей Лапласа

490. The batch of products contains 20% of the reject. Find the probability that among the 400 tested items will fall:
A) not less than 50 and not more than 90 defective items;
B) exactly 50 defective items.

Detailed solution. Decorated in Microsoft Word 2003 (Quest decided to use the formula editor)