## Materials Science and Engineering: An Introduction

$28.0854$ amu
We simply take a weighted average: $w_{28}m_{28}+w_{29}m_{29}+w_{30}m_{30}=M$ where $w_{n}$ is the atomic average and $m_{n}$ is the atomic weight of the specific silicon isotope with mass number $n$. M is the final average weight that we wish to verify. $.9223(27.9769)+.0468*(28.9765)+.0309(29.9738)=$$28.0854$ amu Hence, the atomic weight has been confirmed.