For the following random variables, indicate whether you would expect each to be of low variability (LV), medium variability (MV), or high variability (HV) in normal operating conditions. Explain your answer. Also explain why each one of them could be of LV sometimes and why it could be of HV other times. Be brief and clear.

1. Time to complete this set of study questions.

2. Time for a mechanic to replace a muffler on an automobile.

3. Time until failure of a machine recently repaired by a good maintenance technician.

4. Time until failure of a machine recently repaired by a not-so-good technician.