When a ball is dropped from a top of tower and it covers 24.5 m in thr last second .find the height of the tower

by using second equation of motion 
in which u=0(freely falling object)
a= g( acceleration due to gravity.

in this case you will find the time,which will come 3 seconds
=> total time of the whole journey will be 3 seconds.
so, again by second equation of motion 
u=0, a=9.8m² and t=3sec.
in this case you may find the answer which will come 44.1m (answer)