Question

Gold is 19 times a heavy as water and copper is 9 times as heavy is water. In what ratio should these be mixed to get an alloy 15 times as heavy is waster? `1:1` b. `1:2` c. `2:3` d. `3:2`

Answer 1

Let the weight of water be W therefore, weight of gold `=19W`
and weight of copper `=9W`
therefore weight of alloy `=15W`
Ratio of G:C = 1:y
Therefore total = 1+y
`19W+y(9W)= (1+y)15W`
`19W+9yW = 15W+15Wy`
`4W = 6Wy`
`y = (6W)/(4W)`
`y = 3:2`
which is the required ratio.