Answer:
24.3 amu
Step-by-step explanation:
To find the average atomic mass of a given element, we must first multiply the mass of each isotope by their percent abundance:
24 × 0.7899 = 18.96
25 × 0.100 = 2.5
26 × 0.1101 = 2.86
We can then add each of these masses together:
18.96 + 2.5 + 2.86 = 24.32
To the correct amount of significant figures, this is 24.3 amu