REDOX TITRATION – HOW TO DETERMINE HYDROGEN PEROXIDE CONTENT - Were you cheated by your supplier?

Mr. Black is owner of a small pharmacy shop. He sells a lot of pharmacy products. In his portfolio, there is also a hydrogen peroxide solution sold as a disinfection. Sold solution should be of 3 % w/w. Nevertheless, Mr. Black is not sure, whether his supplier does not cheat and to earn more, he sells him hydrogen peroxide solution with much smaller concentration.

Can you help to Mr. Black and find the concentration of hydrogen peroxide solution from his pharmacy shop? Is the solution sold in his shop OK?

What is the concentration of hydrogen peroxide solution sold in Mr. Black´s pharmacy shop?