Problem Solving
试题详情
题目：
The water from one outlet, flowing at a constant rate, can fill a swimming pool in 9 hours. The water from a second outlet, flowing at a constant rate, can fill the same pool in 5 hours. If both outlets are used at the same time, approximately what is the number of hours required to fill the pool?
选项:
A、0.22
B、0.31
C、2.50
D、3.21
E、4.56
答案:
D
