Of the three numbers, the first is twice the second and the second is twice the third. The average of the reciprocal of the numbers is $\frac{7}{72}$ . The numbers are:
A. 16, 8, 4
B. 20, 10, 5
C. 24, 12, 6
D. 36, 18, 9
Show Answer
Answer-C
Solution-
Solution(By Apex Team)
$\begin{array}{l}\text{Let the number be x.}\\
\text{Then, second number = 2x.}\\
\text{First number = 4x}\\
\therefore\frac{1}{x}+\frac{1}{2x}+\frac{1}{4x}=\frac{7}{72}\times3\\
\Rightarrow\frac{7}{4x}=\frac{7}{24}\\
\Rightarrow4x=24\\
\Rightarrow x=6\end{array}$
So, the number are 24, 12 and 6
