it takes 40 minutes to fill a water tank, and 60 minutes to drain it.
how many hours will it take to fill the tank while draining it the entire time ??
sloveing word problem
2006-10-29 9:22 am
回答 (1)
2006-10-29 9:29 am
✔ 最佳答案
it takes 40 minutes to fill a water tank, and 60 minutes to drain it.how many hours will it take to fill the tank while draining it the entire time ??
注水的速率為 1/40
放水的速率為 1/60
注水及同時放水則：1/40 – 1/60
= (3-2)/120
= 1/120
所以需用
1 / (1/120) = 120分鐘。
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