67. Solving a chemistry problem

3. To determine the composition of water-acetone solutions, the refractive indices of standard solutions were determined:
Acetone content, % 10 20 30 40 50
Refractive index 1.3340 1.3410 1.3485 1.3550 1.3610
Build a calibration graph for the determination of acetone, derive an equation for the dependence of the refractive index on concentration, and determine the content of acetone in the solution, the refractive index of which is 1.3500, from the graph and equation.