Answer: We need to add 1312.5 mililiters.
Step-by-step explanation:
We have a solution of 75ml of 4% of sugar, and we want to know hoy many mililites of 0.30 sugar solution we need to add if we want to get to a solution of 0.50%.
First, we if we add X mililiters of the second solution, we have that the total number of mililiters is:
X + 75 = M
and we also have that for the mixture we need to have that the percentage of sugar in both components corresponds to:
(X*0.003 + 75*0.04) = M*0.005
where i written the percentages as decimals.
now we can write this as:
(X*0.003 + 75*0.04) = (X + 75)*0.005
now we can solve this for X.
(75*0.04 - 75*0.005) = X*0.005 - X*0.003 = X*0.002
2.625 = X*0.002
X = 2.626/0.002 = 1312.5 mililiters.