A wheel that has 6 cogs is meshed with a larger wheel of 14 cogs. When the smaller wheel has made 21 revolutions, then the number of revolutions mad by the larger wheel is:
A. 4
B. 9
C. 12
D. 49
Answer: Option B
Solution(By Examveda Team)
Let the required number of revolutions made by larger wheel be x.Then, More cogs, Less revolutions (Indirect Proportion)
$$\eqalign{ & \therefore 14:6::21:x \cr & \Rightarrow 14 \times x = 6 \times 21 \cr & \Rightarrow x = \frac{{6 \times 21}}{{14}} \cr & \Rightarrow x = 9 \cr} $$
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