What number has to be added to the terms 3 : 5 to make the ratio 5 : 6 ?

A. 6

B. 7

C. 12

D. 13

Answer: Option B

Solution(By Examveda Team)

Let the number to be added be x
Then,
$$\eqalign{ & = \frac{{3 + x}}{{5 + x}} = \frac{5}{6} \cr & \Rightarrow 6\left( {3 + x} \right) = 5\left( {5 + x} \right) \cr & \Rightarrow 18 + 6x = 25 + 5x \cr & \Rightarrow x = 7 \cr} $$