Bunuel wrote:
On Thursday afternoon, two machines, J and R, ran continuously at uniform rates to fill a production order. How long did it take them to fill the order?
(1) The machines began filling the order at 3 p.m.
(2) The machines had filled 1/2 of the order by 3:46 p.m.
Target question: How long did it take the two machines to fill the order? Statement 1: The machines began filling the order at 3 p.m. We have no information about the rates of the machines.
So, statement 1 is NOT SUFFICIENT
Statement 2: The machines had filled 1/2 of the order by 3:46 p.m. We don't know when the machines STARTED.
The machines might have started 20 years ago, in which case it will take them another 20 years to complete the order.
Or the machines might have started 1 minute ago (at 3:55). in which case it will take them another minute to complete the order.
So, statement 2 is NOT SUFFICIENT
Statements 1 and 2 combined The COMBINED statements tell us that it takes the machines 46 minutes to complete HALF the order.
So, it will take them another 46 minutes to complete the remaining HALF of the order.
In other words,
it will take the machines a total of 92 minutes to complete the ENTIRE order. Since we can answer the
target question with certainty, the combined statements are SUFFICIENT
Answer:
Cheers,
Brent
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