A circular rim 28 inches in diameter rotates the same number of inches per second as a circular rim 35 inches in diameter. If the smaller rim makes x revolutions per second, how many revolutions per minute does the larger rim make in terms of x?

I dont know about solution posted by jcgoodchild but if I was to face this question, I would use ratios to solve the question. the ratio of radii is 4/5 and the answer should be a multiple of 4/5 ... I might be wrong. I would really like to have opinion of other people on use of ratios.

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