Answer :
[tex]m_a=4.0026 \cdot 99.9999 \% + 3.0160 \cdot 0.0001 \%= \\ =4.0025959974+0.000003016= \\
=4,0025990134 \ [amu][/tex]
The average atomic mass of helium is 4,0025990134 amu.
The average atomic mass of helium is 4,0025990134 amu.