AFCAT Model Paper 1

Given:
Quantity of mixture = 7.5 litres
The ratio of acid and water in the mixture = 1 : 2
Quantity of mixture in acid = 20%
Calculation:
Let the amount of water be x litre.
Amount of acid in the 7.5 litre mixture ={

1

(1+2)

}×7.5=2.5 litres
Amount of water in the mixture = 7.5 - 2.5 = 5 liters
Now, According to the question
Amount of water in the new mixture = (x + 5)
Amount of acid in the new mixture = 2.5
Now, again according to the question
2.5=(x+7.5)×20%
⇒ 2.5=

(x+7.5)

5

⇒ 12.5=(x+7.5)
⇒ x = 5
∴ The required amount of water is 5 litre.