Multiply this value by the atomic mass of that isotope. Next determine the mass of the isotope. The teacher has said that calculating for a problem with 3 isotopes is all that will be required.
First determine the average atomic mass.
Next determine the mass of the isotope. Relative abundance is the percentage of a particular isotope with a specific atomic mass that occurs in nature. Percentage abundance is always reported as a percentage and it is calculated as. To find the average atomic mass for Carbon.