Discussion

S can copy 50 pages in 10 hours, S and P together can copy 300 pages in 40 hours. In how much time P can copy 30 pages ?

Answer: C

P takes 12 hours.

Find each rate in pages per hour:

\[ \begin{aligned} S &= \frac{50}{10} = 5 \\ S + P &= \frac{300}{40} = 7.5 \\ P &= 2.5 \end{aligned} \]

So P copies 30 pages in \(\frac{30}{2.5} = 12\) hours. The other options do not match a rate of 2.5 pages an hour.

Check: in 40 hours S copies \(5 \times 40 = 200\) pages and P copies \(2.5 \times 40 = 100\), which together make the 300 pages stated.

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