Question

In an 80-litre mixture of milk and water, the ratio of milk to water is 7 : 3. To make this ratio 2 : 1, how many litres of water should be added?

• A. 5 litres
• B. 6 litres
• C. 10 litres
• D. 4 litres

Answer 1

The Correct Option is D

Let's break down this problem step-by-step:

1. Initial Quantities:

• Total mixture: 80 litres
• Milk to water ratio: 7 : 3
• Total ratio parts: 7 + 3 = 10
• Milk quantity: (7/10) * 80 litres = 56 litres
• Water quantity: (3/10) * 80 litres = 24 litres

2. Desired Ratio:

• Desired milk to water ratio: 2 : 1

3. Water Addition:

• Let 'x' litres of water be added.
• New water quantity: 24 + x litres
• Milk quantity remains the same: 56 litres

4. Set Up Equation:

• We want the new ratio to be 2 : 1.
• So, 56 / (24 + x) = 2 / 1

5. Solve for x:

• 56 = 2(24 + x)
• 56 = 48 + 2x
• 2x = 56 - 48
• 2x = 8
• x = 8 / 2
• x = 4

Therefore, 4 litres of water should be added.

The correct answer is Option 4.