Gold is 19 times as heavy as water and copper is 9 times as heavy as water. In what ratio should these be mixed to get an alloy 12 times as heavy as water?
Select:  A) 1:2  B) 3:7  C) 4:1  D) 5:2  E) 6:5
G = 19W   C = 9W   Let 1gm of gold mixed with x gm of copper to get 1+x gm of the alloy   1gm gold + x gm copper = x+1 gm of alloy   19W+9Wx = x+1 * 12W   19+9x = 12(x+1)   x = 7/3   Ratio of gold with copper = 1:7/3 = 3:7   Answer is 3:7
<result>B</result>
Gold is 19 times as heavy as water and copper is 9 times as heavy as water. In what ratio should these be mixed to get an alloy 12 times as heavy as water?