The Readylite Company Produces a Flashlight Which Is Perfectly Reliable

Multiple Choice

The Readylite Company produces a flashlight which is perfectly reliable except for two components: the battery,which has a random failure rate of one in every five hours of operation; and the light bulb,which has a random failure rate of three in every ten hours.Devices,Inc.supplies Readylite with the on-off switch for this flashlight.These switches,on average,fail in fifty hours with a standard deviation of four hours.What service life should Devices specify to have a .8944 probability that a switch will last at least that long before failing?

A) 43 hours
B) 45 hours
C) 46 hours
D) 50 hours
E) 54 hours