Discussion

Question:

From a barrel having 36 litres alcohol, 6 litres are drawn and replaced with water. Then, 12 litres of the mixture is replaced with water. Then, 18 litres of the mixture is replaced with water. Find the final quantity of alcohol in the barrel (in litres).

Explanation:

Step 1:
Since 6 litres out of 36 is removed, fraction of solution removed = 6/36 = 1/6^th
∴ Fraction of solution remaining = 5/6^th
⇒ Alcohol remaining after 1st replacement = 36 × 5/6 = 30 liters.

Step 2:
Now 12 litres out of 36 is removed, fraction of solution removed = 12/36 = 1/3^rd
∴ Fraction of solution remaining = 2/3^rd
⇒ Alcohol remaining after 1st replacement = 30 × 2/3 = 20 liters.

Step 3:
Now 18 litres out of 36 is removed, fraction of solution removed = 18/36 = 1/2
∴ Fraction of solution remaining = 1/2
⇒ Alcohol remaining after 1st replacement = 20 × 1/2 = 10 liters.

∴ Quantity of alcohol remaining in the barrel = 10 litres.

Hence, option (c).

» Your doubt will be displayed only after approval.

Doubts

Feedback