Problem
The time it takes a mechanic to change the oil in a car is exponentially distributed with a mean of 17 minutes.
1. What is the probability density function for the time it takes to change the oil?
f(x) = for x ≥ 0
2. What is the probability that it will take a mechanic less than 18 minutes to change the oil? (Round your answer to four decimal places.)
3. What is the probability that it will take a mechanic between 15 and 17 minutes to change the oil? (Round your answer to four decimal places.)
4. What is the variance of the time it takes to change the oil?