Saturday, October 16, 2010

Machines X and Y produced identical bottles at different constant rates. Machine X, operating alone


Machines X and Y produced identical bottles at different constant rates. Machine X, operating alone  for 4 hours, filled part of a production lot; then machine Y, operating alone for 3 hours, filled the rest  of this lot. How many hours would it have taken machine X operating alone to fill the entire production lot?

(1) Machine X produced 30 bottles per minute.
(2) Machine X produced twice as many bottles in 4hours as machine Y produced in 3 hours.







Statement 1 is insufficient. We have no idea how much of the production lot was left after 4 hours, and we have no idea what speed Y produces at.

Statement 2:


Without any formal math, we see that in 2 hours, it can produce as many items as y did in the 3. So to fill the lot, we need the original 4 hours X worked, plus the 2 hours needed to fulfill y's part of the lot. Or 6 total hours.


Sufficient.

Ans : B 

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