-
The average of three numbers is 77. The first number is twice the second and the second number is twice the third. The first number is :
-
- 33
- 66
- 77
- 132
- 33
Correct Option: D
Let the third number = p
∴ Second number = 2p
First number = 4p
The average of three numbers = 77
Now, p + 2p + 4p = 3 × 77
⇒ 7p = 3 × 77
⇒ p = | = 33 | |
7 |
∴ First number = 33 × 4 = 132
Second method to solve this question with the help of given formula :
Here, a = 2, b = 2, X = 77
First number = | × X | |
1 + b + ab |
First number = | × 77 | |
1 + 2 + 2 × 2 |
First number = | × 77 | |
7 |
First number = 12 × 11 = 132