Question

The LCM and HCF 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

Answer 1

Answer: (C)

84

Let the two numbers be x and 4x
$\therefore$ Product of the two numbers = HCF x LCM
$\Rightarrow x\times 4x=84\times 21\Rightarrow 4x^2=84\times 21$

$\Rightarrow$ $x^2=\frac{84\times 21}{4}=21\times 21\Rightarrow x=21$

$\therefore$ Larger number $=4\times 21=84$