Answer

As per given question,

when body is dropped from height s,then using the equatuion of motion,

s=1/2g(t-1)²  ...(1)

When height of tower is increased four times:

4s=1/2g(t-2)²   ...(2)

DIvide (1) by (2) and simplify,

t-2=2(t-1)

 

Although time comes out to be 0 in this case,so we are talking of a hypothetical situation here.