Two chips are being considered for use in a certain system. the life time of chip 1 is modeled by a gaussian random variable with mean 20,000 hours and standard deviation 4000 hours.(the probability of negative life time is negligible.)the lifetimeofchip2is 22,0001000 hours.(the probability of negative life time is negligible.) which chip is preferred if the target life time of the system is 20,000 hours