Civil Service Exam Reviewer · Ratio and Proportion · hard
A gear with 28 teeth rotating at 160 rpm drives a gear with 35 teeth. How fast does the second gear rotate?
- 200 rpm
- 160 rpm
- 153 rpm
- 128 rpm
Answer
D. 128 rpm
Solution
Teeth × rpm is the same for meshing gears: 28 × 160 = 35 × N → N = 128 rpm (inverse proportion).
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