Question

Help..

Answer 1

basically you are calculating a weighted average

ex: if you have a class where tests are 80% of your grade and homework is 20% then your grade is

80% test average + 20% homework average

Answer 2

applying this logic to your problem:

isotope 1's contribution is 78.9 amu + 0.128
repeat this process w/ the other isotopes and add up the three results

then units are amu

Answer 3

249.70

Answer 4

78.9 amu* 0.128

Answer 5

should be a multiplication sign not an addition sign

Answer 6

so 78.9*0.128 + 82.9*0.131 + 86.9*0.741

Answer 7

85.352 to 4 sig figs so it would be 85.35

Answer 8

hm not quite. notice all the numbers in the table are XX.X so each only has 3 sig figs

Answer 9

85.4 amu

Answer 10

good