Solution of problem N3993 probability theory total prob

3993. 60% of the picture tubes in the warehouse of a television studio are made by plant No. 1, and the rest by plant No. 2. The probability of the fact that the kinescope of factory No. 1 does not fail during the warranty period of service is 0.9, and for the kinescope of factory No. 2 this probability is 0.7. Find the likelihood that at random taken kinescope will withstand the warranty period.