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 larger of the two numbers is

A 12

B 48

C 84

D 108

Correct Answer: Option C

Let the numbers be x and 4x. then

\(x\times4x=84\times21\;\Leftrightarrow\;x^2=\frac{84\times21}4\Leftrightarrow\;x=21\)

Hence Larger Number = 4x = 84