Question

$A$ and $B$ are two alloys of gold and copper in the ratio $7:2$ and $7:11$ respectively. If equal quantities of these two alloys are melted to from a new alloy $C$, then the ratio of gold and copper in $C$ is $:$

• A. $6:5$
• B. $9:4$
• C. $12:7$
• D. $7:5$

Answer 1

Answer: (D)

$7:5$

Gold in $C=(\frac{7}{9}+\frac{7}{18})$units

$=\frac{7}{6}$ units.

Copper in $C=(\frac{2}{9}+\frac{11}{18})$ units

$=\frac{5}{6}$ units

$\therefore$Gold:Copper$=7:6::5:6=7:5$