An alloy of copper and bronze weight 50g It contains 80 Copper How much copper should be added to th......

An alloy of copper and bronze weight 50g. It contains 80% Copper. How much copper should be added to the alloy so that percentage of copper is increased to 90%?

Initial quantity of copper =80/100 x 50 = 40 g 

And that of Bronze = 50 - 40 = 10 g

Let 'p' gm of copper is added to the mixture

= (50 + p) x 90/100 = 40 + p

= 45 + 0.9p = 40 + p

= p = 50 g

50 gms of copper is added to the mixture, so that the copper is increased to 90%.

Hence, option 2 is the correct answer.

By: Amit Kumar