SOLUTION: if you need 50lbs of an alloy that is 50% nickel how many pounds of an alloy with 80% must be mixed with an alloy that is 40% nickel

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Question 461079: if you need 50lbs of an alloy that is 50% nickel how many pounds of an alloy with 80% must be mixed with an alloy that is 40% nickel
Answer by oberobic(2304) About Me  (Show Source):
You can put this solution on YOUR website!
With problems like this, you have to keep track of how much "pure" stuff you need.
It says you need 50 lb of 50% nickel.
50*.5 = 25 lbs of pure nickel
.
The total of 50 lb is divided between the amount of 40% nickel and 80% nickel
x = the amount of 40% nickel
(50-x) = the amount of 80% nickel
.
.4x + .8(50-x)=25
.4x + 40 - .8x = 25
-.4x = -15
x = 37.5 lb of 40% alloy
.
50-x = 12.5 lb of 80% alloy
.
Check your answer.
.4*37.5 = 15
.8*12.5 = 10
15+10 = 25
.
Done.