Civil Service Exam Reviewer · Ratio and Proportion · hard
A gear with 70 teeth rotating at 300 rpm drives a gear with 35 teeth. How fast does the second gear rotate?
- 150 rpm
- 600 rpm
- 300 rpm
- 335 rpm
Answer
B. 600 rpm
Solution
Teeth × rpm is the same for meshing gears: 70 × 300 = 35 × N → N = 600 rpm (inverse proportion).
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