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Of the three numbers, the first number is twice of the second and the second is thrice of the third number. If the average of these 3 numbers is 20, then the sum of the largest and smallest numbers is
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- 24
- 42
- 54
- 60
- 24
Correct Option: B
Let the third number be p.
∴ Second number = 3p
and first number = 6p
∴ 6p + 3p + p = 3 × 20
⇒ 10p = 60
⇒ p = 6
∴ Required sum = 6p + p = 7p = 7 × 6 = 42
Second method to solve this question with the help of given formulas :
Here, a = 2, b = 3, X = 20
| Largest Number = | X | |
| 1 + b + ab |
| Largest Number = | × 20 | |
| 1 + 3 + 2 × 3 |
| Largest Number = | × 20 = 36 | |
| 10 |
| Smallest Number = | X | |
| 1 + b + ab |
| Smallest Number = | × 20 | |
| 1 + 3 + 2 × 3 |
| Smallest Number = | × 20 = 6 | |
| 10 |
Sum = 36 + 6 = 42
