Question 276407
<br>
Also ignoring the fact that a 40% solt solution is not possible....<br>
Any 2-part mixture problem like this can be solved informally (and quickly, if the numbers are "nice") using the logical fact that the ratio in which the two ingredients must be mixed is exactly determined by where the target percentage lies between the percentages of the two ingredients.<br>
For this problem...<br>
(1) The target percentage of 40% is "3 times as close" to 20% as it is to 100% (the difference between 20 and 40 is 20; the difference between 40 and 100 is 60; 20 is one-third of 60)
(2) That means the amount of the 20% ingredient must be 3 times the amount of the 100% ingredient<br>
The given amount of the 20% ingredient is 24 kg, so the amount of the added 100% salt must be one-third of 24 kg, which is 8 kg.<br>
ANSWER: 8 kg<br>