Answer:
Using some dilutions of the mother solution
Explanation:
If there is a valid process by which the mother solution can be diluted with precision, the results must be in the range that are "normal".
If there are different dilutions that shows different results, but by graphing and extrapolating they show the same results as the mother solution, then the first  measurement is correct.
This is also a method used to calibrate an instrument or to confirm the concentration of the mother solution.
check the graph.
Hope this info is useful.