3. Two electrical components are connected in series, so if one component fails, then the whole system fails. The lifetime of the rst component is exponential with average lifetime 4 years, while the second component is also exponential with average lifetime 5 years. Assume the two components are independent. How long can you expect the whole system to last? Is it 4 years? 4. In the situation above, how likely is it that component 1 fails before component 2