Two varieties of steel, A and B, have a ratio of iron to chromium as 5:1 and 7:2, respectively. Steel C is produced by mixing alloys A and B at a ratio of 3:2. What is the ratio of iron to chromium in C?
Choose the correct choice from the following choices
A) 17 : 73	B) 78 : 14	C) 45 : 30	D) 73 : 17	E) 4 : 9
In 6 parts of alloy A, 5 parts are iron, and 1 part is chromium.   In 9 parts of alloy B, 7 parts are iron and 2 parts are chromium.   First, to compare the two alloys, get the same number of parts in total - we can use 18. So we have:   In 18 parts of alloy A, 15 parts are iron and 3 are chromium.   In 18 parts of alloy B, 14 parts are iron and 4 are chromium.   So combining 3 of A with 2 of B, we'd be combining 45 and 28 parts of iron, or 73 parts of iron, with 9 and 8 of chromium, or 17 of chromium, so 73 to 17 is the answer.   ANSWER:73 : 17
<result>D</result>
Two varieties of steel, A and B, have a ratio of iron to chromium as 5:1 and 7:2, respectively. Steel C is produced by mixing alloys A and B at a ratio of 3:2. What is the ratio of iron to chromium in C?