410. The telegraph station accepts the digital text. Due to interference, the probability of mistaken reception of any digit does not change during the whole reception and is 0.01. Considering the methods of individual digits as independent events, find the probability that in the text containing 1100 figures: a) there will be exactly 7 errors; B) the number of incorrectly received digits will be less than 20.

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