Subject: General Aptitude · Chapter: Average · Exam: 2005 · Marks: · Difficulty:
Out of three numbers, the first is twice the second and is half of the third. If the average of the three numbers is 56, then difference of first and third numbers is
(a)12
(b)20
(c)24
(d)48
Answer
Answer (as printed): D
Explanation
Let the second number be $x$. Then, first number $=2 x$, third number $=4 x$. $$\begin{aligned} & \therefore 2 x+x+4 x=56 \times 3 \Rightarrow 7 x=168 \Rightarrow x=24 \\ & \therefore \text { Required difference }=4 x-2 x=2 x=48 \end{aligned}$$
Explanation as extracted from the printed page; notation may be imperfect.