Sir/ mam pls slove the query

Dear Student,
Solution) Total distance travelled = 1000 km 400 meter
                                                           = 1000 + 0.4 km
                                                           = 1000.4 km (1km=1000m)
Total time taken
$$\begin{gathered} =15\frac{1}{2}hour and 30 minutes \\ =\frac{(15\times 2)+1}{2} +\frac{30}{60} \left(because 1hour=60minutes\right) \\ =\frac{30+1}{2}+\frac{1}{2} \\ =\frac{31}{2}+\frac{1}{2} \\ =\frac{32}{2} \\ =16hour \end{gathered}$$
Now, as we know that,
$Average speed=\frac{total dis\tan ce }{total time }=\frac{1000.4}{16}=62.525km/hr$
Regards!