In the afternoon, a student reads 250 pages at the rate of 50 pages per hour. In the evening, when she was tired, she reads 150 more pages at the rate of 20 pages per hour. What was her average rate of reading, in pages per hour?
Time taken in reading 250 pages @ 50 pages/hr = 250/50 hr = 5 hr Time taken in reading 150 pages @ 20 pages/hr = 150/20 hr = 15/2 hr ∴ Total time taken in reading 400 pages = 5 + 15/2 = 25/2hr. ∴ Required average rate of reading = (400 ×2)/25 = 32 pages/hr