Two alloys contain tin and iron in the ratio of 1:2 and 2:3. If the two alloys are mixed in the proportion of 3:4 respectively (by weight). find the ratio of tin and iron in the newly formed alloy.

Question

How to solve this question by ratio and proportion method and mixture and alligation method.

Answer 1

Let the weights of tin and iron be S and F respectively. The first alloy consists of S/3+2F/3, the second 2S/5+3F/5. The mixture contains 3(S/3+2F/3)/7+4(2S/5+3F/5)/7=(S+2F+1.6S+2.4F)/7=(2.6S+4.4F)/7=2(1.3S+2.2F)/7. Ratios of tin and iron in the mixture are 1.3:2.2 or 13:22.