Official Guide Explanation:
Data Sufficiency #68




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Solution and Metadata

Question: 68
Page: 278
Difficulty: 6 (Moderately Difficult)
Category 1: Word Problems > Work Problems > 3+ inputs
Category 2: Word Problems > Work Problems > 2 inputs

Explanation: This question looks fairly complicated, discussing simultaneous and combined rate for three machines. Most GMAT questions only ask you to consider two machines in scenarios like these.

Statement (1) is sufficient. As it turns out, the question is simpler than it looked. Instead of finding the individual rates of all three machines, we can treat M and P as one machine. If we know M and P's combined rate, and we know the combined rate of all three machines, we can find K's individual rate. We don't need to consider M and P as separate, because nowhere up to this point in the question are they treated as such.

Statement (2) is insufficient. As in (1), this gives us the combined rate of two of the three machines. However, it doesn't give us the information we're looking for. Knowing the combined rate of K and P, we can find the rate of M. But since K and P are treated as one unit, we can't separate their individual rates. Choice (A) is correct.

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