The lives of parts are often expressed as the number of cycles of operation that a specified percentage of a population will exceed before experiencing failure. The symbol L is used to designate this...

The lives of parts are often expressed as the number of cycles of operation that a specified percentage of a population will exceed before experiencing failure. The symbol
L
is used to designate this definition of life. Thus we can speak of
L
₁₀
life as the number of cycles to failure exceeded by 90 percent of a population of parts. Given a normal distribution model, with a mean of = 122.9 kilocycles and standard deviation of
s
_L
= 30.3 kilocycles, estimate the corresponding
L
₁₀
life.