Gold is 19 times as heavy as water and copper 9 times as heavy as water. The ratio in which these two metals be mixed so that the mixture is 15 times as heavy as water is:
1 : 2
2 : 3
3 : 2
19: 135
Explanation:
Let the ration of gold and copper that taken be a:l
$\dfrac{19a + 9I}{a+I}$ = $\dfrac{15}{I}$
19a+9I = 15a+15I
19a-15a=15I-9I
4a=6I
2a=3I
$\dfrac{a}{I} $ = $\dfrac{3}{2}$
Gold and copper are taken in the ratio 3 : 2
Let the ration of gold and copper that taken be a:l
$\dfrac{19a + 9I}{a+I}$ = $\dfrac{15}{I}$
19a+9I = 15a+15I
19a-15a=15I-9I
4a=6I
2a=3I
$\dfrac{a}{I} $ = $\dfrac{3}{2}$
Gold and copper are taken in the ratio 3 : 2