Question: One of the authors took his minivan in for repair recently because the air conditioner was cutting out intermittently. The mechanic identified the problem as dirt in a control unit. He said that in about 75% of such cases, drawing down and then recharging the coolant a couple of times cleans up the problem-and costs only $60. If that fails, then the control unit must be replaced at an additional cost of $100 for parts and $40 for labor.

a) Define the random variable and construct the probability model.

b) What is the expected value of the cost of this repair?

c) What does that mean in this context? Oh-in case you were wondering-the $60 fix worked!