Gold is 12 times as heavy as aluminum and copper is 5 times as heavy as aluminum.In what ratio gold and copper should be mixed to get an alloy 8 times of aluminum.
A is weight of Aluminium.
Gold is 12 times as heavy as aluminum and copper is 5 times as heavy as aluminum and the alloy have 8 times of aluminum.
Gold = 12A, Copper = 5A,  Alloy = 8A
Let ratio of Gold and Copper be 1 : x, so the total alloy = (1+x)
Acc to question,
$$12A + x\times5A = (1+x)8A$$
$$12A +5Ax = 8A+8Ax$$
$$x = \frac{4}{3}$$
Ratio of Gold and Copper be 1 : x = 3 : 4
Option B is correct.
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