Civil Service Exam Reviewer · Ratio and Proportion · hard
A gear with 56 teeth rotating at 140 rpm drives a gear with 32 teeth. How fast does the second gear rotate?
- 245 rpm
- 80 rpm
- 140 rpm
- 164 rpm
Answer
A. 245 rpm
Solution
Teeth × rpm is the same for meshing gears: 56 × 140 = 32 × N → N = 245 rpm (inverse proportion).
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