Question

The ratio of ages of A,B, C is 5:7:12.
If age of B is more than two and half years than age of A , then what was the age of C two years before?
1) 13 years
2)10 years
3)12 years
4)15 years​

Answer 1

Step-by-step explanation:

since age of $A$,$B$ and $C$ are in ratio of $5:7:12$

therefore,

let age of $A$ be $5x$

let age of $B$ be $7x$

let age of $C$ be $12x$

since,$B$ is more than two and half years old then $A$

therefore,

$B = A + 2 + \frac{1}{2}$

=> $7x = 5x + \frac{5}{2}$

=> $7x = \frac{10x + 5}{2}$

=> $14x = 10x + 5$

=> $14x - 10x = 5$

=> $4x = 5$

=> $x = \frac{ 5}{4}$

therefore,

current age of $C$ is $12 \times \frac{5}{4} = 15$years.

therefore,

age of $C$ two years before is $15-2 = 13$years.