David can type a 50-page paper in 8 hours. Last month David and Andy together typed a 50-page paper in 6 hours. How long would Andy take to type a 50-page paper by himself?

1 Answer
Roella W.
Apr 14, 2016

24 hours

Explanation:

Typing 50 pages in 8 hours means that David types 50/8 pages per hours =25/4 pages per hour. In six hours he would have typed 25/4 * 6 = 75/2 pages.

Therefore Andy typed 50 - 75/2 pages which is (100-75)/2 = 25/2 pages.

25/2 pages in 6 hours means that Andy types at 25/(2*6) pages per hour, which is 25/12 pages per hour.

50/(25/12) = 50*12/25 = 24 hours to type 50 pges.

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