The average of three numbers is 40. The first number is

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The average of three numbers is 40. The first number is twice the second and the second one is thrice the third number. The difference between the largest and the smallest numbers is

1. 30
2. 36
3. 46
4. 60

Correct Option: D

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

∴	6p + 3p + p	= 40
	3

⇒ 10p = 120 ⇒ p = 12
∴ Required difference = 6p – p = 5p = 5 × 12 = 60
Second method to solve this question with the help of given formulas :
Here, a = 2, b = 3, X = 40

Largest Number = First Number =	3ab	× X
	1 + b + ab

Largest Number =	3 × 2 × 2	× 40
	1 + 3 + 2 × 2

Largest Number =	18	× 40 = 72
	10

Smallest Number = Third Number =	3	× X
	1 + b + ab

Smallest Number =	3	× 40
	1 + 3 + 2 × 3

Smallest Number =	3	× 40 = 12
	10

Difference = 72 – 12 = 60