What would be the concentration of a solution made by diluting 45.0 mL of 4.2 M KOH to 250 mL?
The concentration would be 0.76 mol/L.
The most common way to solve this problem is to use the formula
In your problem,
This makes sense. You are increasing the volume by a factor of about 6, so the concentration should be about ¹/₆ of the original (¹/₆ × 4.2 = 0.7).