Correct. Regroup and multiply: $\displaystyle{\left({4}\times{7.2}\right)}{\left({{10}}^{{7}}\times{{10}}^{{3}}\right)}={\left({28.8}\right)}{\left({{10}}^{{7}}\times{{10}}^{{3}}\right)}\usepackage{cmbright}\Huge\$

Use the product rule: $\displaystyle{\left({28.8}\right)}\times{{10}}^{{{7}+{3}}}={28.8}\times{{10}}^{{10}}\usepackage{cmbright}\Huge\$

Convert 28.8 into scientific notation, regroup, and use the product rule: $\displaystyle{2.88}\times{\left({{10}}^{{1}}\times{{10}}^{{10}}\right)}={2.88}\times{{10}}^{{{1}+{10}}}={2.88}\times{{10}}^{{11}}\usepackage{cmbright}\Huge\$