Correct. Setting up an equation that relates Asha's rate of work (1 room in 1.5 hours), Bipin's rate of work (1 room in h hours), Cassie's rate of work (1 room in 3 hours), and the group's rate of work (1 room in 0.5 hours), you find $\displaystyle\frac{{1}}{{1.5}}+\frac{{1}}{{h}}+\frac{{1}}{{3}}=\frac{{1}}{{0.5}}\usepackage{cmbright}\Huge\$ . Note that this can be rewritten as $\displaystyle\frac{{2}}{{3}}+\frac{{1}}{{h}}+\frac{{1}}{{3}}=\frac{{2}}{{1}}\usepackage{cmbright}\Huge\$ . Solving for h yields h=1, so it would take Bipin 1 hour to paint the room by himself.