A cyclist rides 16.0 km east, then $8.0 \mathrm{km}$ west, then $8.0 \mathrm{km}$ east, then $32.0 \mathrm{km}$ west, and finally $11.2 \mathrm{km}$ east. If his average velocity is $24 \mathrm{km} /$ h, how long did it take him to complete the trip? Is this a reasonable time?