SOLUTION: A solution of 75% pesticide is to be mixed with a solution of 35% pesticide to form 440 liters of a 43% solution. How many liters of the 75% solution must be used?

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Question 585605: A solution of 75% pesticide is to be mixed with a solution of 35% pesticide to form 440 liters of a 43% solution. How many liters of the 75% solution must be used?
Found 3 solutions by mananth, stanbon, josmiceli:
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Acid percent ---------------- quantity
Pesticide type I 75.00% ---------------- x liters
Pesticide type II} 35.00% ------ 440 - x liters
Mixture 43.00% ---------------- 440

75.00%x+35.00%(440-x)=43.00% * 440
75x+35( 440-x)= 18920
75x+15400-35x=18920
75x-35x =18920-15400
40x= 3520
/ 40
x=88 liters 75.00% Pesticide type I
352 liters 35.00% Pesticide type II}

m.ananth@hotmail.ca

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
A solution of 75% pesticide is to be mixed with a solution of 35% pesticide to form 440 liters of a 43% solution. How many liters of the 75% solution must be used?
----------------------
Equation:
active + active = active
0.75x + 0.35(440-x) = 0.43*440
-----
75x + 35*440 - 35x = 43*440
40x = 8*440
x = (1/5)*440
x = 88 liters (amt of 75% solution needed)
----
440-x = 352 liters (amt. of 35% solution needed)
================================================
Cheers,
Stan H.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = liters of 75% pesticide needed
Let +b+ = liters of 35% pesticide needed
given:
(1) +a+%2B+b+=+440+
(2) +%28+.75a+%2B+.35b+%29+%2F+440+=+.43+
-----------------------------
(2) +.75a+%2B+.35b+=+.43%2A440+
(2) +.75a+%2B+.35b+=+189.2+
(2) +75a+%2B+35b+=+18920+
(2) +15a+%2B+7b+=+3784+
Multiply both sides of (1) by +7+
and subtract (1) from (2)
(2) +15a+%2B+7b+=+3784+
(1) +-7a+-+7b+=+-3080+
+8a+=+704+
+a+=+88+
and, since
(1) +a+%2B+b+=+440+
(1) +88+%2B+b+=+440+
(1) +b+=+440+-+88+
(1) +b+=+352+
88 liters of 75% pesticide are needed
352 liters of 35% pesticide are needed
check:
(2) +%28+.75%2A88+%2B+.35%2A352+%29+%2F+440+=+.43+
(2) +%28+66+%2B+123.2+%29+%2F+440+=+.43+
(2) +189.2+%2F+440+=+.43+
(2) +189.2+=+.43%2A440+
(2) +189.2+=+189.2+
OK