A hypothetical element has three main iso- topes with mass numbers of 81, 83, and 84. If 17.00% of the isotopes have a mass number of 81 amu and 35.00% of the isotopes have a mass of 83 amu, what atomic weight should be listed on the periodic table for this element?

Answer 1

17% is h1
35% is 83
Then 48% is 84

(0.17)*81 + (0.35)*83 + (0.48)*84 = ?