250. The probability that a pair of shoes, taken at random from the manufactured batch, turns out to be 1st grade, is equal to 0.8. Find the probability that among the 1800 pairs entering the control, the number of pairs of first-class shoes will be no less than 1400 and no more than 1460.

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