题目

Two machines, working simultaneously at their respective constant rates, can print 400 sheets in 5 hours. If one machine can print 200 sheets in 3 hours, what is the rate of the other machine, in sheets per hour?


选项

A.

B.

C.

D.

80

E.

200

解析

设两台机器分别为A和B 5小时内:A + B = 400张 1小时内:A + B = 80张 设机器A在3小时内打印200张纸 因此,机器A每小时可打印\(\frac{200}{3}\)张纸 因此: \[ \begin{align*} \frac{200}{3} + B &= 80 \\ B &= \frac{40}{3} \end{align*} \] 因此,答案为选项A。
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