Answer: Option B
Explanation:
Let the number of boys and girls be x and y respectively. Then From question, (x - y ) = 12% of (x + y) ⇒ x/y = 3/25 (x + y ) ⇒ 25x - 25y = 3x + 3y ⇒ 22x = 28y ∴ x / y = 28 / 22 = 14 / 11
Answer: Option C
For dividing 12 into two whole numbers, the sum of the terms of the ratio must be a factor of 12. so, they cannot be in the ratio 3 :2.
If ₹ 782 be divided into three parts, proportional to : : , then the first part is:
Answer: Option D
Given ratio = : : = 6 : 8 : 9.
Let the required number be N, From question, (54 - N) / (71 - N) = (75 - N) / (99 - N) ⇒ (54 - N) x (99 - N) = (75 - N) x (71 - N) ⇒ N2 - 153N + 5346 = N2 - 146N + 5325 ⇒ 7N = 21 ∴ N = 3
Let 0.8 : 0.2 : : 0.2 : N Then 0.8 x N = 0.2 x 0.2 ∴ N = ( 0.2 x 0.2) / 0.8 = 0.04 / 0.08 = 4/80 = 0.05
Less length, less weight From question, 13 : 6 : : 23.4 : W ⇒ 13 x W = 6 x 23.4 ∴ W = (6 x 23.4) /13 = 10.8 kg
7 : 5 = 7/15 = 0.466 15 : 23 = 15/23 = 0.652 17 : 25 = 17/25 = 0.68 and 21 : 29 = 0.724 ∴ The smallest one is 7 : 15.
Let the number be N, From question, (6 + N) / (14 + N) = (18 + N) / (38 + N) ⇒ (6 + N) x (38 + N ) = (18 + N ) x (14 + N ) ⇒ N2 + 44N + 228 = N2 + 32N + 252 ⇒ 12N = 24 ∴ N = 2
∵ (7 + N) / (13 + N) = 2/3 ⇒ 3(7 +N) = 2(13 + N) ∴ N = 5
∵ 20 kg of brass contains zinc = 13 kg ∴ 100 kg of brass contains zinc = (13/20) x 100 kg. = 65 kg.
: 
: 
, then the first part is:
1st part = ₹
