Question

The H.C.F. and L.C.M. of two numbers are 84 and 21 respectively. If the ratio of the two numbers is 1:4, then the large of tthe two numbers is ;

• A. 12
• B. 48
• C. 84
• D. 108

Answer 1

The correct option is C 84

Consider the numbers will be $x$ and $4x$,

Then,

$\begin{array}{c}x\times 4x=84\times 21\\ x^2=\frac{84\times 21}{4}\\ x=21\end{array}$

Hence, the correct option is $C$