Shortcut Trick
Alcohol from Container A = (4 ÷ 5) × 10 = 8 L and Water from A = 10 − 8 = 2 L
Alcohol from Container B = (5 ÷ 7) × 14 = 10 L and Water from B = 14 − 10 = 4 L
Total Alcohol in new mixture = 8 + 10 = 18 L
Total Water in new mixture = 2 + 4 = 6 L
Required Ratio of Alcohol to Water = 18 : 6 = 3 : 1
∴ The correct answer is 3:1.
Alternate Method
Given:
Ratio of alcohol to water in Container A = 4:1
Ratio of alcohol to water in Container B = 5:2
Mixture drawn from Container A = 10 liters
Mixture drawn from Container B = 14 liters
Formula Used:
Quantity of component = (Ratio of component ÷ Total ratio parts) × Total quantity
Container A
10 L (Ratio 4:1)
Alc: 8L | Wat: 2L
Container B
14 L (Ratio 5:2)
Alc: 10L | Wat: 4L
New Mixture
Alc: 18L | Wat: 6L
Ratio → 3:1
Calculations:
⇒ In Container A, the sum of ratio parts = 4 + 1 = 5
⇒ Quantity of alcohol drawn from A = (4 ÷ 5) × 10 = 8 liters
⇒ Quantity of water drawn from A = (1 ÷ 5) × 10 = 2 liters
⇒ In Container B, the sum of ratio parts = 5 + 2 = 7
⇒ Quantity of alcohol drawn from B = (5 ÷ 7) × 14 = 10 liters
⇒ Quantity of water drawn from B = (2 ÷ 7) × 14 = 4 liters
⇒ Total alcohol in the third container = 8 + 10 = 18 liters
⇒ Total water in the third container = 2 + 4 = 6 liters
⇒ Ratio of alcohol to water in the new mixture = 18 : 6
⇒ Simplifying the ratio by dividing both sides by 6, we get 3 : 1
∴ The correct answer is 3:1.
Additional Information
Multiple Mixtures Concept
When components from multiple different mixtures are mixed together, individually calculate the absolute quantities of each component from every source. Sum these respective quantities up to find the final total amount before constructing the new ratio.
Alligation Method
Used to find the ratio in which two mixtures must be mixed to obtain a desired concentration. The fundamental rule relates the quantities: (Quantity of Cheaper) ÷ (Quantity of Dearer) = (Price of Dearer − Mean Price) ÷ (Mean Price − Price of Cheaper).
Replacement Method
If a certain volume 'y' is replaced 'n' times from a total pure volume 'x', the final quantity of the original pure substance left is given by the formula: Final Quantity = Initial Quantity × (1 − y/x)n.