Question

50 kg of an alloy of lead and tin contains 60% of lead. How much lead must be added to the alloy to contain 75% of led?

Answer 1

Quantity of lead in 50 kg of alloy = 60% of 50 kg = ​​​​​​kg = 30 kg.


Let the required quantity of lead to be added be x kg.

Then, weight of lead = (30 + x) kg.

And, weight of new alloy = (50 + x) kg.

Percentage of lead in new alloy =



4(30 + x) = 3(50 + x)

⇒ 120 + 4x = 150 + 3x

⇒ 4x - 3x = 150 - 120

⇒ x = 30