A hospital needs 40 L of a 10% solution of
disinfectant. How many liters of a 25%
solution and a 9% solution should be mixed to
obtain this 10% solution?

Step-by-step explanation:

i didnt exactly answer this but i found someone who did

(pasted)  i still hope it helps

Let x and (40L-x) represent the 20% and 4% solutions respectively

Mixing the 20% and 1%  to form 40L of 15% solution

.20x + .04(40L-x) = .15*40L

             .16x = .11*40L

                x = .11*40L/.16

                x = 27.5L, the amount of the 20% solution.  

                    12.5L,the amount of the 4% solution  (40L - 27.5L)

CHECKING our Answer

.20*27.5L + .04*12.5L = 5.5L + .5L = 6L = .15*40L

Which tells us incidentally there is 6L of disinfectant in the final solution.

dunno

step-by-step explanation:

good luck on your studies! : )

david edward.