An alloy contains 40% of silver, 30% of copper and 30% of nickel. How much silver (in kg) should be added to 25 kg of the alloy so that the new alloy contains 50% of silver?
Answer & explanation
Correct answer: option 1
Total quantity of alloy = 25 kg,
Ratio
Silver : Copper : Nickel
4 : 3 : 3
⇒ (4 + 3 + 3)x = 25,
⇒ 10 x = 25,
⇒ x = 2.5,
Quantity
Silver : Copper : Nickel
4 x 2.5 : 3 x 2.5 : 3 x 2.5
Quantity 10 : 7.5 : 7.5
⇒ To make silver 50 %,
⇒ Silver = Copper + Nickel
⇒ 10 + x = 7.5 + 7.5
⇒ x = 15 - 10
⇒ x = 5 Kg
Hence 5 Kg silver should be added to alloy.