Решение задачи N1482 теория вероятностей Пуассона

1482. A message of 2,000 characters is transmitted via the communication channel. The probability of distortion of each symbol when transmitting a message is 0.001. What is the probability that:
1) will there be 5 distorted symbols in the received message?
2) the message will be accepted correctly, if for this purpose the number of distorted symbols should not exceed 3?

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