Question

The Yankee Doodle Electronics Company of Yokohama manufactures and exports a low-priced transistor radio. Since the company does not produce its own transistors, it must purchase them from two different suppliers. 40% of its radios contain Brand A transistors and 60% contain Brand B transistors. The operating lives of the radios containing the two transistor brands are normally distributed and have the following parameters:

                        Brand A: Mean life = 1000 hrs., standard deviation = 200 hrs.

                        Brand B: Mean life = 1200 hrs., standard deviation = 100 hrs.

If a customer in the U.S. bought one of these radios (selected at random), what is the probability that its operating life would be:

a)   Between 1100 and 1200 hours.

Answer 1

Solution Let & denotes mean life of rauss XIA ~ Normal with mandelelooshes o=200hrs X/B~ Horme with mean life = 1200 hrs o-loohrs PL100<x</2003 - Pl1oox xla </200].CA) + plnoX / 821100] (B) . = (0.8413-0.6915 30.40 + (0.5060 -0.0227)0:60 - 0.0599 + 0.2864 - 0.3463