The time it takes a machine to perform an operation depends on the state it enters when the start button is pushed. There are three known states: fast, moderate, and slow. When it is in the fast state, it takes 2 minutes to perform the operation. When it is in the moderate state, it takes 4 minutes to perform the operation. When it is in the slow state, it takes 7 minutes to perform the operation. Studies indicate that the machine goes into the fast state when the start button is pushed 60% of the time; it goes into the moderate state 25% of the time; and it goes into the slow state 15% of the time. What is the expected time it takes the machine to perform the operation?