Ram can copy 60 pages in 15 hours. If Ram and Riya together can copy 180 pages in 30 hours, then in how many hours can Riya copy 20 pages?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 10 hours.
Ram's copying rate = 60/15 = 4 pages/hour
Copying rate of Ram and Riya = 180/30 = 6 pages/hour
Riya's copying rate = 6 - 4 = 2 pages/hour
Riya takes to copy 20 pages = 20/2 = 10 hours
Therefore, Riya can copy 20 pages in 10 hours.