3986. The store received refrigerators of three firms in the amount of 35, 20 and 4, respectively. The probability that the refrigerator will not fail during the warranty period is: for the first company, 0.95; for the second - 0.8; for the third - 0.9. The purchased fridge was reliable. Find the probability that this refrigerator is manufactured by a second firm.

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