A Chemistry lаb is cоnducting а inventоry оf the mаss of dry chemicals in a supply cabinet. Based on the data in the table, calculate the following information. Mass (grams) Number of chemicals 0 - 19 5 20 - 39 8 40 - 59 12 60 - 79 5 a) Determine the width of the classes. b) Calculate the mean mass.