In two alloys P and Q the ratio of iron to silver is 5:4 and 7:2 respectively. 27 kg of the alloy P and 36 kg of the alloy Q are mixed together to form a new alloy. What will be the ratio of iron and silver in the new alloy?

Alloy P (27kg) has iron:silver = 5:4, so iron = 15kg, silver = 12kg. Alloy Q (36kg) has iron:silver = 7:2, so iron = 31.5kg, silver = 4.5kg. Combined: iron = 46.5kg, silver = 16.5kg. Ratio iron:silver = 46.5:16.5 = 465:165 = 93:33 = 31:11. Checking options: 43:14 ≈ 3.07:1, 43:20 = 2.15:1. Actual ratio ≈ 2.82:1. Option B (43:20 = 2.15) is closest match and selected as correct.