SOLUTION: A Chemist has 100g of 25% acid solution. How much of these solution he needs to drain and replaced with 70% acid solution to obtain 100g of 60% acid solution
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Question 1013544: A Chemist has 100g of 25% acid solution. How much of these solution he needs to drain and replaced with 70% acid solution to obtain 100g of 60% acid solution Found 4 solutions by josgarithmetic, lwsshak3, ikleyn, greenestamps:Answer by josgarithmetic(39815) (Show Source):
You can put this solution on YOUR website! A Chemist has 100g of 25% acid solution. How much of these solution he needs to drain and replaced with 70% acid solution to obtain 100g of 60% acid solution
let x=amt of 25% solution to drain and replace with 70% solution
25%
25%(100-x)+70%x=60%100
25-.25x+.70x=60
.50x=35
x=70
How much of these solution he needs to drain and replaced with 70% acid solution to obtain 100g of 60% acid solution? 70 mg
You can put this solution on YOUR website! .
A Chemist has 100g of 25% acid solution. How much of these solution he needs to drain and replace
with 70% acid solution to obtain 100g of 60% acid solution
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Calculations in the post by @lwsshak3 are incorrect and lead to wrong answer.
I came to bring a correct solution.
Let x = the amount of 25% solution to drain and replace with 70% solution (in grams).
The balance equation for the acid is
0.25*(100-x) + 0.7x = 0.6*100
25 - 0.25x + 0.70x = 60
0.45x = 35
x = 35/0.45 = 77 grams, or 77.7778 grams, approximately. ANSWER
Here is a solution using a non-traditional method that can be used to solve any 2-part mixture problem like this. This method can be especially fast and easy if the numbers in the problem are "nice" (which in this problem they are not....)
(1) Use a number line if it helps to observe/calculate that 60% is 35/45 = 7/9 of the way from 25% to 70%.
(2) That means 7/9 of the mixture must be the 70% acid solution which is being added.
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