Question

The ratio of the number of bulbs in two rooms A and B was 3 : 8. If 6 bulbs are removed from room B, the new ratio becomes 6 : 13. Find the number of bulbs in room B. 
1. 36
2. 38
3. 34
4. 32

Answer 1

Correct Answer - Option 4 : 32

Given: The ratio of the number of bulbs in two rooms A and B was 3 : 8. If 6 bulbs are removed from room B, the new ratio becomes 6 : 13.

Formula: If the ratio of A and B is a : b, we can assume the numbers A and B to be ak and bk respectively, where k is a constant. Ratio of A and B when A increased by D and B decreases by E = (ak + D)/(bk + E)

Calculation: Let the number of bulbs in A and B be 3x and 8x respectively.

(3x)/(8x - 6) = 6/13

⇒ 39x = 48x – 36

⇒ 9x = 36

⇒ X = 4

Bulbs in room B = 8x = 8 × 4 = 32