Ratio And Proportion Ques 37
Question-
The respective ratio between the present ages of $A$ and $B$ is $4: 5$ and that between the present ages of $C$ and $D$ is $7: 5$. The average of the present ages of A, B, C and $D$ is 27 years and D’s age 3 years hence will be 14 years less than A’s present age. What is B’s present age? (in years)
(1) 30
(2) 25
(3) 40
(4) 50
(5) 20
(IBPS SO (IT Officer) CWE (Prelim Exam) 30.12.2017)
Show Answer
Correct Answer: (3)
Solution: (3)
$A: B=4: 5=4 x$ and $5 x$
$C: D=7: 5=7 y$ and $5 y$
$\therefore A+B+C+D=27 \times 4=108$
$\Rightarrow 4 x+5 x+7 y+5 y=108$
$\Rightarrow 9 x+12 y=108$
$\Rightarrow 3 x+4 y=36 \ldots .$. (i)
Again,
$5 y+3=4 x-14$
$\Rightarrow 4 x-5 y=17$…. (ii)
By equation (i) $\times 5+$ (ii) $\times 4$,
$15 x+20 y+16 x-20 y$ $=180+68$
$\Rightarrow 31 x=248$
$\Rightarrow x=\frac{248}{31}=8$
$\therefore$ B’s present age $=5 x$ $=5 \times 8=40$ years
BETA
