Ok .. for this we are using the Equations of Motion to solve the sum ....

We apply : s = ut + 1/2 atxt in the downward direction...

where :::: s is the distance travelled or displacement
u is the initial velocity which Suzy drops the rock ( 0 m/s1)
t is the time taken ( 0.223 sec )
a is the gravitational acceleration ( 9.8 m/s2 )

So if we apply the equation we get ::

s= ut+ 1/2 atxt

So ,,, s = 0 x 0.223 sec + 1/2 x 9.8 m/s2 x 0.223 sec x 0.223 sec

We get :: s = 0.24367 m as the distance travelled.

So when it was freely dropped from the roof, the rock has travelled a distance of 0.24367 m in 0.223 sec due to the gravitational acceleration of 9.8 m/s2.

So, the height of the roof from the window is 0.24367 m.

The height of the roof from the ground is = 8.2 m + 0.24367 m
= 8.44367 m.

Hope this helps !!

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