Multiple choice

An alloy contains the Copper and Aluminium in the ratio of 7 : 4. While making the weapons from this alloy, 12% of the alloy gets destroyed. If there is 12 kg of aluminium in the weapon, then the weight of the alloy required will be ?

  1. 32.5 kg.

  2. 37.5 kg.

  3. 42.5 kg.

  4. 45 kg.

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Alloy has Cu:Al = 7:4, so Al is 4/11 of total alloy. 12% is destroyed, so remaining is 88%. If 12 kg Al is in weapon: original Al needed = 12/0.88 = 13.636 kg. Since Al is 4/11 of total, total alloy = 13.636 × (11/4) = 37.5 kg. Option B is correct. Account for loss first, then use ratio.

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