Of the three numbers, the first is twice the second and

Home » Aptitude » Average » Question

Of the three numbers, the first is twice the second and the second is thrice the third. If the average of the three numbers is 10, the largest number is :

1. 12
2. 15
3. 18
4. 30

Correct Option: C

Let the third number be p.
∴ Second number = 3p
First number = 6p

Now,	p + 3p + 6p	= 10
	3

⇒ 10p = 30 ⇒ p = 3
∴ The largest number = 6p = 6 × 3 = 18.
Second method to solve this question with the help of given formulas :
a = 2, b = 3, X = 10

Largest number =	3ab	× X
	1 + b + ab

Largest number =	3 × 2 × 3	× 10
	1 + 3 + 2 × 3

Largest number =	18	× 10 = 18
	10