It takes less force to lift the object in the water than on land, since the water is helping with the weight of the object.
The formula for maximum distance is
X = (V^2 / g) * sin (2 * theta)
10 = (V^2 / 9.8) * sin (2 * 20)
10 = (V^2 / 9.0) * sin(40)
10 = (V^2 / 9.8) * 0.324
v^2 = (10 / 0.324) * 9.8
V^2 = 302.47
v = 17.39 meters/sec (takeoff speed)
The horizontal speed is = Takeoff Speed * Cos(20) = 17.39 * 0.910 = 16.341 meters / sec
Recall that
At its maximum height 
, the toy will have 0 vertical velocity, so that
For the toy to reach this maximum height, it takes time 
such that
which means it takes twice this time, i.e. 
, for the toy to reach its original position.
The velocity of the toy when it falls 1.0 m below its starting point is
where we took the negative square root because we expect the toy to be moving in the downward direction.
Average speed = (total distance covered) / (time to cover the distance)
Ian's total distance = (2km + 0.5km + 2.5km) = 5 km
Ian's total time = 3 hours
Average speed = (5km) / (3 hours)
Average speed = 1.66 km/hr
