SOLUTION: How many litres of 15% weedkiller mixture must be added to 5 litres of 10% weedkiller mixture to make a 12% weedkiller mixture?

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Question 1095527: How many litres of 15% weedkiller mixture must be added to 5 litres of 10% weedkiller
mixture to make a 12% weedkiller mixture?
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
let x equal the number of liters of 15% weedkiller.

your equation is .15 * x + .10 * 5 = .12 * (x + 5)

simplify to get .15 * x + .10 * 5 = .12 * x + .12 * 5

simplify further to get .15 * x + .5 = .12 * x + .6

subtract .12 * x from both sides and subtract .5 from both sides and simplify to get .03 * x = .1

divide both sides by .03 to get x = .1 / .03 = 3.333333333 rounded to 9 decimal digits.

you would need 3.333333333 liters of 15% solution to be added to 5 liters of 10% solution to get 8.333333333 liters of 12% solution.

.15 * 3.333333333 = .5
.10 * 5 = .5

.5 + .5 = 1

5 + 3.333333333 = 8.333333333

1 divided by 8.333333333 = .12 which is equal to 12%.

solution looks good.

you would need 3 and 1/3 liters of 15% solution to be added to 5 liters of 10% to get 8 and 1/3 liters of 12% solution.

in decimal form rounded to 2 decimal digits, you would need 3.33 liters of 15% solution to be added to 5 liters of 10% solution to get 8.33 liters of 12% solution.