Question

LaCrosse Technology is one of many manufacturers of atomic clocks. It makes an atomic digital watch that is radio-controlled and that maintains its accuracy by reading a radio signal from a WWVB radio signal from Colorado. It neither loses nor gains a second in 20 million years. It is powered by a 3-volt lithium battery expected to last three years. Suppose the life of the battery has a standard deviation of .3 years and is normally distributed
c.) Compute the length-of-life value for which 10% of the watch's batteries last longer