3959. Electric bulbs are produced in two factories. The first plant produces 60% of the total number of light bulbs, the second - 40%. The production of the first plant contains 70% of standard lamps, the second - 80%. The store receives products from both plants. What is the probability that the lamp purchased in the store will be standard?

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