Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 7 : 5 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ? Pick one
A) 1 : 1  B) 2 : 3  C) 5 : 2  D) 10 : 11  E) 7 : 9
Mixture A has a total of 7 + 5= 
<gadget id="calculator">7 + 5</gadget>
<output>12</output>
12 parts. If in the final mixture this represents 6 parts, then the total number of parts in mixture B should be  (12/6)*3= 
<gadget id="calculator"> (12/6)*3</gadget>
<output>6</output>
6.   So, we should take of mixture B a quantity with 3 and 6 parts, respectively.   This will give us in the final mixture (7 + 3) : (5 + 6), which means 10:11   Answer 10 : 11.
<result>D</result>
Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 7 : 5 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ?