Solution of problem N3156 probability theory

Solution of problem N3156 probability theory

3156. A correct hex dice is thrown 7 times. What is the probability that:
a) more than three times will fall out 4 points on the upper edge of the bone;
b) 4 points on the top of the bone will fall twice?

Additional information:

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