SOLUTION: john completed 20 problems in 12 minutes.At this rate, how long will it take him to complete the remaining 7 problems?

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Question 350464: john completed 20 problems in 12 minutes.At this rate, how long will it take him to complete the remaining 7 problems?
Answer by mananth(16946)   (Show Source): You can put this solution on YOUR website!
20 problems 12 minutes
7 problems - ?
direct proprtion
7/20*12
=21/5
=4.2 minutes

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