we know that
1 km-------------> 1000 m-----------> 100000 cm
1 min------------> 60 sec
then
10 km is------------> 10*100000------> 1000000 cm
and
54 min is------------> 54*60------------> 3240 sec
hence
[average speed]=distance/time
[average speed]=1000000 cm/3240 sec------------> 308.64 cm/sec
the answer is
308.64 cm/sec
