Two different machines, A and B, were used together at the same time to print a book. It took two hours for the book to be printed. If only Machine A was used, it would have taken another 4 hours. How long would it take to print the same book if only Machine B was used?
Solution
Machine A only ----- 2 hours + 4 hours = 6 hours
6 hours ----- Machine A printed whole book
2 hours ----- Machine A printed 1/3 book
The other 2/3 of the book was printed by Machine B
2 hours ----- Machine B printed 2/3 book
2/3 book ----- 2 hours
3/3 book ----- 3 hours
Answer: It would take 3 hours if Machine B was used only.
Monday, August 11, 2008
Maha Bodhi Sch 2007 PSLE Math Prelim Q48
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