Multiple choice

A bucket contains a mixture of two liquids A and B in the proportion 7: 5 . If 9 litres of the mixture is replaced by 9 litres of liquid B, then the ratio of the two liquid becomes 7: 9. How much of the liquid A was there in the bucket? एक बाल्टी में 7: 5 के अनुपात में दो तरल A और B का मिश्रण है। यदि 9 लीटर मिश्रण को 9 लीटर तरल B से बदल दिया जाता है, तो दोनो तरल का अनुपात 7: 9 हो जाता है। बाल्टी में कितना तरल A था?

  1. 28

  2. 35

  3. 42

  4. 14

  5. 21
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Initial ratio 7:5 means 7x and 5x liters. Removing 9 litres removes 7/12×9 = 5.25 L of A and 3.75 L of B. After adding 9 L of B: A = 7x - 5.25, B = 5x - 3.75 + 9. New ratio 7:9. Solving gives x = 3, so A = 21 liters.

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