Answer :
if 24 sec is taken for 240 m of platform
then,
240/24 sec will be taken for 1m which comes as 1 sec
then for 650 m platform it will take (650*10)sec=6500 sec
then,
240/24 sec will be taken for 1m which comes as 1 sec
then for 650 m platform it will take (650*10)sec=6500 sec