please explain how to apply dilution factor here. Ty

Make a dilution of PNP using your buffer as the diluent. Add 0.5mL of 1.25mM p-nitrophenol (PNP) to a 25 or 50mL beaker using a micropipette. Dilute the PNP by adding 9.5mL of your buffer solution that you made from step 1 (use a graduated cylinder to measure the buffer). The PNP is located in the fume hood in the back of the room, along with the PNP disposal container where you will dispose of your PNP waste at the end of lab. Based on the dilution information given to you, what is the dilution factor being made for PNP? Hint: The amount of PNP added is 1 part stock solution. How many parts of buffer (diluent) did you add? After you determine that number, add the 1 part of stock to the parts of diluent and that is your dilution factor. Example: 1 part stock to 3 parts diluent would be a 1:3 dilution and the dilution factor is 4x