A system has two failure modes. One failure mode, due to external conditions, has a constant failure

A system has two failure modes. One failure mode, due to
external conditions, has a constant failure rate of 0.07 failure per year. The
second, attributed to wearout, has a Weibull distribution with a characteristic
life of 10 yr and a shape parameter of 1.8. Determine the system reliability
for a design life of 1 yr. Find by trial and error the median time to failure.