A Cistern contains a mixture of two liquids A and B in the ratio of 7 : 5, when 9 liter of mixture is drawn off and replaced with B then the ratio of A and B becomes 7 : 9. Find the quantity of A initially.
Answer & explanation
Correct answer: option 3
Method one:
The ratio A : B
7 : 5
So, the answer will be in the multiple of (7). Therefore, 21 liters is the answer.
Method two:
A : B
7 : 5
↓+4R = 9 ltrs
7 : 9
1R = \(\frac{9}{4}\)
Final Qty. 16R = \(\frac{9}{4}\) × 16 = 36 liters = Initial Qty.
Initial ratio = 7 : 5 = 12
12R = 36
1R = 3
Qty. of A initially = 7R = 3 × 7 = 21 liters