Решение задачи N4129 теория вероятностей Лапласа

4129. The computer system contains 50 identical microchips. The probability that any microchip will work at a given time is 0.9. To perform a certain operation, it is required that at least 30 microchips be in working condition.
a) What is the probability that the operation will be completed successfully?
b) What is the probability that 47 microchips will work?

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