I think that the correct answer is 33
1.
Height h = 240 feet
We insert it into formula.

Now we solve this for t:

We have two answers as the rocket will pass this height on it's way up and down.
2.
Height h = 0 feet
We insert it into formula.

Now we solve this for t:

We do not consider solution -1 as the time can not be negative. Our solution is 5s.
3.
Height at bottom of hill h = 0 feet
We insert it into formula.
A=(απr^2)/360=(απd^2)/1440 (r^2=d^2/4)
α=1440A/(πd^2)
s=απd/360 (where s=arc length) so
s=(1440Aπd)/(360πd^2)
s=4A/d and since A=10mi^2 and d=20mi
s=(4*10)/20
s=2 miles