Question

Out of three numbers, the ratio between the first and the second number is 6 : 7, and the ratio between the second and the third number is 8 : 9. If the difference between the first and the third number is 150, then find the average of the first and the second number.
1. 502
2. 602
3. 520
4. 620

Answer 1

Correct Answer - Option 3 : 520

The ratio of first and second number is 6 : 7

The ratio of second and third number is 8 : 9

After combine both we get,

⇒ 6 : 7 : : 8 : 9

⇒ 48 : 56 : 63 ⇒ 48x, 56x and 63x.

The given difference of first and third is = 150

⇒ 63x - 48x = 150

⇒ 15x = 150

⇒ x = 10

put the value of x we get,

First number = 48x = 48 x 10 = 480

Second number = 56x = 56 x 10 = 560

Third number = 63x = 63 x 10 = 630

Average of First and second number we get,

(480 + 560)/2 = 1040/2 = 520

Hence, "520" is the correct answer.