To calculate the average atomic mass multiply the fraction by the mass number for each isotope then add them together. Change the percent abundance to a decimal by dividing by 100 3. The weighted average takes into account the mass and percentage abundance of each isotope.
One can calculate the atomic mass of the element with these tips.
To accomplish this we usually use an approach called the weighted average. In this problem the percent abundance represents the relative importance of each isotope. Next determine the masses of each isotopeUsing the same example above this would be 35 and 37 amu respectively. The weighted average takes into account the mass and percentage abundance of each isotope.