# In two alloys the ratios of copper to tin are 3 : 4 and 1 : 6 respectively. If 7 kg of the first alloy and 21 kg of the second alloy are mixed togethe

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In two alloys the ratios of copper to tin are 3 : 4 and 1 : 6 respectively. If 7 kg of the first alloy and 21 kg of the second alloy are mixed together to form a new alloy, then the ratio of copper to tin in the new alloy is:
1. 3 : 11
2. 1 : 4
3. 3 : 7
4. 4 : 11

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Correct Answer - Option 1 : 3 : 11

Given:

The ratio of copper to tin of 1st alloy = 3 : 4

The ratio of copper to tin of 2nd alloy = 1 : 6

Weight of 1st alloy = 7 kg

Weight of 2nd alloy = 21 kg

Calculation:

The quantity of copper in 7 kg alloy = (3/7) × 7 = 3 kg

The quantity of tin in 7 kg alloy = (4/7) × 7 = 4 kg

The quantity of copper in 21 kg alloy = (1/7) × 21 = 3 kg

The quantity of tin in 21 kg alloy = (6/7) × 21 = 18 kg

New alloy = 1st alloy + 2nd alloy

Total quantity of copper in new alloy = 3 + 3 = 6 kg

Total quantity of tin in new alloy = 4 + 18 = 22 kg

The ratio of copper to tin in new alloy = 6 : 22 = 3 : 11

∴ The ratio of copper to tin in the new alloy is 3 : 11.