Решение задачи N1167 теория вероятностей Лапласа

1167. 400 samples of ore are to be examined. The probability that the industrial iron content in each sample is above 50% is 0.8. Find the probability that among the 400 samples tested, the ore with an industrial iron content of more than 50% is at least 300.

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