A fold density is 19 times greater than the water and for copper it is 9 times. At what ratio you can mix gold
and copper to get 15 times denser than water. ?  Choose the correct choice from the following options
A) 3 : 1	B) 3 : 2	C) 3 : 5	D) 3 : 8	E) 3 : 7

Rationale: suppose x units of gold are mixed with y units of copper to make ( x + y ) units of alloy which is 15 times denser than water . then 19 * x + 9 * y = 15 * ( x + y ) = > 19 * x - 15 * x = 15 * y - 9 * y = > 4 * x = 6 * y = > x / y = 3 / 2 so gold and copper should be mixed respectively in the ratio of 3 : 2 answer : b
Answer: B