4250. In two identical boxes are pencils. It is known that 1/4 of the pencils in the first box and 1/5 of the pencils in the second are characterized by TM hardness. At random, one box is selected and one pencil is drawn at random from it. It turned out to be hardness tm. What is the likelihood that it is removed from the second box?

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