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题库 / Prep2007E2-DS-179
Working independently at their respective constant rates, pumps X and Y took 48 minutes to fill an empty tank with water. What fraction of the water in the full tank came from pump X ?
(1) Working alone at its constant rate, pump X would have taken 80 minutes to fill the tank with water.
(2) Working alone at its constant rate, pump Y would have taken 120 minutes to fill the tank with water.
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
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设总量为1，x注的水占总量的比例为48*x的速度/1，求出x的速度便能解出来。
X,Y共同工作需要花48分钟，那么只需知道X或者Y工作需要花的时间就能求出另外一方花的时间，工作时间的比例即能求出工作效率之比，在一个tank里面注水的比例也能求出