We need to add 400 ml of the 40% solution.
What is concentration?
Being focused in some way. attention being focused on a single thing, in particular. I can't concentrate with all that noise around me. a concentration or major within an academic discipline.
What is volume?
A three-dimensional space's actual size when a closed surface encloses it. Take the area or shape that a substance, such as a solid, liquid, gas, or plasma, occupies as an example. The cubic meter, a S.I.-derived unit, is also frequently used to represent volume numerically.
We take the amount times the percent concentration and add what we mix to get the final concentration
We need the final mixture to be 30% and we have 200 +x milliliter added together so that will be the amount in the container
200 * 10 % + x* 40 % = (200+x) *30%
Change the percent to decimal form
200 * .10 + x* .40 = (200+x) *.30
Distribute the .30
20 + .4x = 60+.3x
Subtract .3x from each side
20 + .4x-.3x = 60+.3x-.3x
20 +.1x = 60
Subtract 20 from each side
20-20 +.1x = 60-20
.1x = 40
Divide by .1
.1x/.1 = 40/.1
x=400
Therefore, We need to add 400 ml of the 40% solution
Learn more about concentration from the given link.
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