SOLUTION: John wants to make an alloy of which 30% will be copper. He uses 500g which has 20% copper and X grams which has 70% copper. Find the value of X. Thank you.

Question 1149122: John wants to make an alloy of which 30% will be copper.
He uses 500g which has 20% copper and X grams which has 70% copper.
Find the value of X.
Thank you.
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
500 g*0.20 Cu=100 g Cu
x g*0.70 is 0.70x g Cu
Total is 500+x g of combined with 100+0.7x g Cu
that ratio, or (100+0.7x)/(500+x)=0.30
multiply both sides by 500+x
100+0.7 x=150+0.3 x
0.4x=50
divide by 0.4
x=125 g of the 70% Cu
This is 625 g total with 187.5 g Cu=0.3
RELATED QUESTIONS
How much of an alloy with 30% copper must be added to 25 pounds of a second alloy which... (answered by nyc_function)

How much of an alloy with 30% copper must be added to 25 pounds of a second alloy which... (answered by josgarithmetic)

I am truly stumped with this one. An alloy weighing 20 kg is 30% copper. How many kg... (answered by Earlsdon)

A metallurgist needs to produce 10kg of an alloy which is 65% copper and 35% tin. He has... (answered by mananth)

A metallurgist has one alloy cantaining 20% copper and another containing 70% copper.... (answered by funmath)

If an alloy is 20% zinc and 80% copper, how many grams of each will be required to make... (answered by hamsanash1981@gmail.com)

a sculptor wants to cast a bronze statue from an alloy that is 60% copper. he has 30... (answered by Alan3354)

How many kg of a 45% copper alloy must be added to 62kg of a 60% copper alloy to form an... (answered by stanbon)

how much of 75% copper alloy should be melted into 62 kg of a 35% copper alloy to produce (answered by mananth)