A and B are two alloys of gold and copper prepared by mixing metals in the ratio 7 : 2 and 7 : 11, respectively. If equal quantities of the alloys are melted to form a third alloy C, the ratio of gold and copper in C is |
A) 5 : 7
B) 5 : 9
C) 7 : 5
D) 9 : 5
Correct Answer: C
Solution :
Quantity of gold in \[A=\frac{7}{9}\,kg\] |
and quantity of copper in \[A=\frac{2}{9}\,kg\] |
Quantity of gold in \[B=\frac{7}{18}\] |
Quantity of copper in\[B=\frac{11}{18}\] |
\[\therefore \] Required ratio |
\[=\,\,\frac{\left( \frac{7}{9}+\frac{7}{18} \right)}{\frac{2}{9}+\frac{11}{18}}\,\,=\,\,\frac{14+7}{4+11}=\frac{21}{15}=\frac{7}{5}\] |
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