Question:
How many litres of a 30% alcohol solution should be added to 40 litres of a 60% alcohol solution to prepare a 50% solution?
How many litres of a 30% alcohol solution should be added to 40 litres of a 60% alcohol solution to prepare a 50% solution?
Show Hint
Write the alcohol content on both sides as an equation and solve for the added volume, or use the alligation rule.
Updated On: Aug 18, 2026
- 30
- 20
- 24
- 32
Show Solution
Verified By Collegedunia
The Correct Option is B
Solution and Explanation
Step 1: Set up the unknown.
Let \(V\) litres of the 30% alcohol solution be added to the 40 litres of 60% alcohol solution.
Step 2: Write the alcohol balance equation.
The alcohol contributed by the first solution is \(0.30V\), and the alcohol contributed by the second solution is \(0.60 \times 40 = 24\) litres. The total mixture has volume \(V + 40\) litres and needs to be 50% alcohol, so: \(0.30V + 24 = 0.50(V + 40)\).
Step 3: Expand and simplify.
\(0.30V + 24 = 0.50V + 20\).
Step 4: Solve for V.
\(24 - 20 = 0.50V - 0.30V\), so \(4 = 0.20V\), giving \(V = 20\).
Step 5: Verify and match with options.
Adding 20 litres of 30% solution gives \(0.30 \times 20 = 6\) litres of alcohol, and the 40 litres of 60% solution gives 24 litres of alcohol. Total alcohol = 30 litres in a total volume of 60 litres, which is exactly 50%. This confirms \(V = 20\), matching option (2). None of the other volumes, 30, 24 or 32 litres, satisfy this balance check.
Let \(V\) litres of the 30% alcohol solution be added to the 40 litres of 60% alcohol solution.
Step 2: Write the alcohol balance equation.
The alcohol contributed by the first solution is \(0.30V\), and the alcohol contributed by the second solution is \(0.60 \times 40 = 24\) litres. The total mixture has volume \(V + 40\) litres and needs to be 50% alcohol, so: \(0.30V + 24 = 0.50(V + 40)\).
Step 3: Expand and simplify.
\(0.30V + 24 = 0.50V + 20\).
Step 4: Solve for V.
\(24 - 20 = 0.50V - 0.30V\), so \(4 = 0.20V\), giving \(V = 20\).
Step 5: Verify and match with options.
Adding 20 litres of 30% solution gives \(0.30 \times 20 = 6\) litres of alcohol, and the 40 litres of 60% solution gives 24 litres of alcohol. Total alcohol = 30 litres in a total volume of 60 litres, which is exactly 50%. This confirms \(V = 20\), matching option (2). None of the other volumes, 30, 24 or 32 litres, satisfy this balance check.
Was this answer helpful?
0
0
Top SNAP Quantitative Aptitude Questions
- Rahul starts a business with ₹ 8000. After $6$ months, Sanjay joins with some capital. If their profits after one year are equal, find Sanjay's investment.
- A watch is bought for ₹ 1950 in cash and sold for ₹ 2200 on one-year credit. If the interest rate is $10\%$ p.a., find the trader's gain/loss.
- An article is listed at ₹ 65. A customer bought this article for ₹ 56.16 and got two successive discounts, the first being $10\%$. What was the other discount rate allowed by the shopkeeper?
A company has $50{,}000$ preferred shares with dividend $20\%$ and $20{,}000$ common shares; par value of each share is ₹ 10. The total profit is $₹ 1{,}80{,}000$, of which $₹ 30{,}000$ is kept in reserve and the rest distributed to shareholders. Find the dividend percent paid to common shareholders.
A man buys apples at a certain price per dozen and sells them at eight times that price per hundred. What is his gain or loss percent?
View More Questions
Top SNAP Mixtures and Alligation Questions
- An alloy of gold and silver weighs 50 gms and contains 80% gold. How much gold should be added to the alloy so that the percentage of gold increases to 90%?
- How many kgs of tea worth Rs. 25 per kg must be blended with 30 kgs of tea worth Rs. 30 per kg so that by selling the blended variety at Rs. 30 per kg there should be a gain of 10%?
- 300 gms of salt solution has 40% salt in it. How much salt should be added to make it 50% in the solution?
- A mixture of 12 kg of wheat flour costing Rs. 16 per kg and 4 kg of corn flour costing Rs. 2 per kg is sold at Rs. 16 per kg. What is the profit made in selling 40 kg of the mixture?
Top SNAP Questions
- In a retail outlet, the average revenue was Rs.10,000 per day over a 30 day period. During this period, the average revenue on weekends (total 8 days) was Rs. 20,000 per day. What was the average daily revenue on weekdays?
- Two different prime numbers X and Y, both are greater than 2, then which of the following must be true?
- It takes 6 hours for pump A, used alone, to fill a tank of water. Pump B alone takes 8 hours to fill the same tank. A, B and another pump C all together fill the tank in 2 hours. How long would pump C take, used alone, to fill the tank?
- A swimming pool can be filled by pipe A in 3 hours and by pipe B in 6 hours, each pump working on its own. At 9 am, pump A is started. At what time will the swimming pool be filled if pump B is started at 10 am?
- The sum of prime numbers that are greater than 60, but less than 70 is :
View More Questions