Question

Gold is 19 times as heavy as water and copper is $9$ times as heavy as water. In what ratio should these metals be mixed so that the mixture may be $15$ times as heavy as water?

• A. $2:3$
• B. $2:4$
• C. $3:2$
• D. $4:2$

Answer 1

Answer: (C)

$3:2$

Let the ration of gold and copper that taken be $a:l$

$\frac{19a+9l}{a+l}=\frac{15}{1}$

$19a+9l=15a+15l$

$19a-15a=15l-9l$

$4a=6l$

$2a=3l$

$\frac{a}{l}=\frac{3}{2}$

$\therefore$ Gold and copper are taken in the ratio $3:2$