Multiple choice

In an alloy, the ratio of copper to zinc is $5\,\colon\,2$. If $1.250:kg$ of zinc is mixed in $17.500:kg$ of alloy, then what will be the new ratio of copper to zinc?

  1. $\;2\,\colon\,1$
  2. $\;2\,\colon\,3$
  3. $\;3\,\colon\,2$
  4. $\;1\,\colon\,2$
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A Correct answer
Explanation

Initial alloy: 17.5 kg, ratio 5:2. Copper = (5/7)*17.5 = 12.5 kg, Zinc = (2/7)*17.5 = 5 kg. Add 1.25 kg zinc: New Zinc = 6.25 kg. New ratio = 12.5 : 6.25 = 2 : 1.

AI explanation

In the original 17.500 kg alloy, the ratio of copper to zinc is 5 to 2, meaning copper is 5/7 of the mixture and zinc is 2/7. This gives 12.5 kg of copper and 5 kg of zinc. After adding 1.250 kg of zinc, the new zinc mass is 6.25 kg. The new ratio of copper to zinc is 12.5 to 6.25, which simplifies to 2 to 1.

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