Subject: General Aptitude · Chapter: Problems on Ages · Exam: · Marks: · Difficulty:
Ten years ago, a man was seven times as old as his son. Two years hence, twice his age will be equal to five times the age of his son. What is the present age of the son? (Railways, 2006)
(a)12 years
(b)13 years
(c)14 years
(d)15 years
Answer
Answer (as printed): C
Explanation
Let son's age 10 years ago be $x$ years. Then, man's age 10 years ago $=7x$ years. Son's present age $=(x+10)$ years, man's present age $=(7x+10)$ years. $$2[(7x+10)+2]=5[(x+10)+2] \Rightarrow 2(7x+12)=5(x+12) \Rightarrow 14x+24=5x+60 \Rightarrow 9x=36 \Rightarrow x=4.$$ Son's present age $=(x+10)$ years $=(4+10)$ years $=14$ years.
Explanation as extracted from the printed page; notation may be imperfect.