Question

alloy is of 50 kg it contains 60% lead and rest tin. how much more lead should be added to make its percentage 75% in the alloy?

Answer 1

50 kg has 60% lead it means 50*60/100=30 kg lead and remaining 20kg tin , if we need to make lead 75% then tin should be 25% , currently we have 20kg tin in alloy if that should become 25% then 75% is three times it , ie 20*3=60kg , we already have 30kg lead in alloy , so if we add another 30kg to make it 60 , then tin still will be 20kg and lead will be 60kg , total alloy is 80kg , 75% of 80 , ie 60kg is lead , so answer is we need to add 30 kgs of lead