Shortcut Trick
Remaining mixture after removing 4 Litres = 35 − 4 = 31 Litres.
Since the ratio remains 3 : 2, Milk = (3/5) × 31 = 18.6 Litres and Water = (2/5) × 31 = 12.4 Litres.
Add 4 Litres of pure Milk: New Milk = 18.6 + 4 = 22.6 Litres.
New Ratio = 22.6 : 12.4 = 226 : 124 = 113 : 62.
∴ The correct answer is 113 : 62.
Alternate Method
Given:
Total volume of mixture = 35 Litres
Initial Ratio (Milk : Water) = 3 : 2
Quantity replaced = 4 Litres
Calculations:
⇒ Initial Milk = (3/5) × 35 = 21 Litres
⇒ Initial Water = (2/5) × 35 = 14 Litres
⇒ Milk in 4 Litres mixture = (3/5) × 4 = 2.4 Litres
⇒ Water in 4 Litres mixture = (2/5) × 4 = 1.6 Litres
⇒ Remaining Milk = 21 − 2.4 = 18.6 Litres
⇒ Remaining Water = 14 − 1.6 = 12.4 Litres
⇒ After adding 4 Litres of Milk, New Milk = 18.6 + 4 = 22.6 Litres
⇒ New Ratio (Milk : Water) = 22.6 : 12.4
⇒ New Ratio = 226 : 124 = 113 : 62
∴ The correct answer is 113 : 62.
Additional Information
Mixture Replacement Rule
When a portion of a mixture is removed, the ratio of the components in the remaining mixture and the removed part remains the same as the original ratio.
Ratio Definition
A ratio a : b indicates that the quantity is divided into (a + b) parts, where the first component represents a/(a+b) of the total.
Successive Replacement Formula
Final Quantity = Initial Quantity × (1 − Replaced Volume/Total Volume)n, where n is the number of times the process is repeated.