Whenever 3 type A machines and 5 type B machines operate for the same amount of time, the two groups produce the same number of units. A plant has type A and type B machines in the ratio 2:3. All machines operate normally for 4 hours. For the next 6 hours, one-fourth of the A machines are unavailable and the remaining A machines run at 80% of normal speed; one-third of the B machines are unavailable and the remaining B machines run at 125% of normal speed. One-eighth of the units made in the first 4 hours require rework during the next 6 hours. Reworking one unit uses the capacity that could otherwise produce one-half of a new unit, and every reworked unit becomes usable.