Answer :
[tex] the\ mean\ hickness\ of\ Vicki's\ books= \frac{28\ cm}{10} =2.8\ cm\\\\28\ cm\ \rightarrow\ 10\ boocks\\120\ cm\ \rightarrow\ x\\\\x= \frac{120\cdot 10}{28} \approx42.9\\\\Ans.\ Vicki\ can\ put\ 42\ books.[/tex]