To archive a concentration of 40%, you need to add 62.5 kg of salt.
How much salt must we add?
First, we have 150kg of aqueous salt solution with a concentration of the 15%, which means that the 15% of 150kg is salt, so we have:
0.15*150kg = 22.5 kg of salt.
Now we want to add a quantity M of salt, such that the new concentration of salt is of 40%.
The new mass of the mixture will be:
150kg + M
The new mass of salt will be:
22.5kg + M
The concentration of salt, in decimal form, will be:
(22.5kg + M)/(150kg + M)
The above quotient must be equal to 0.4 (40% in decimal form), then we solve:
(22.5kg + M)/(150kg + M) = 0.4
(22.5kg + M) = 0.4*(150kg + M)
(22.5kg + M) = 60kg + 0.4*M
M - 0.4*M = 60kg - 22.5kg
0.6*M = 37.5kg
M = (37.5 kg)/0.6 = 62.5kg
So you need to add 62.5kg of salt.
If you want to learn more about concentrations, you can read:
https://brainly.in/question/14278665
