Question

A 20% acid solution is mixed with a 70% acid solution to get 50 liters of a 40% solution.

How much of the 70% solution is used?

20 liters
25 liters
30 liters

Answer 1

\[
x+y=50\\
0.20x+0.70y = 0.40(x+y)
\]

Answer 2

If you solve for \(y\), you will get the answer.

Answer 3

thank you

Answer 4

Does the equation make sense?

Answer 5

i tried that but for the second equation i did .2x+.7y=.4
and thats all so thats what i did wrong and yeah it makes sense thanks so much

Answer 6

yep, need to think of the second equation in terms of the amount of stuff...0.2 liters of acid in each of x liters of 20% solution + 0.7 liters of acid in each of y liters of 70% solution = 0.4 liters of acid in each of 50 liters of 40% solution

Answer 7

30 litres

Answer 8

check your answer:

adding 30 liters of 70% acid to 20 liters of 20% acid:
30*0.7 + 20*0.2 = 21+4=25 liters of acid in 50 liters of solution or a 50% concentration.
You want a 40% concentration.

Answer 9

sorry 20 liters

Answer 10

other one is 30..

Answer 11

30*.2 + 20*.7 = 6 + 14 = 20 liters of acid in 50 liters of solution = 40%, that's correct.

Answer 12

heartbreaking to do the problem right and get it wrong because you mislabeled or misinterpreted the results!

Answer 13

lol.. happens with me all the times

Answer 14

thanks