What we need first is the formula to calculate maximum horizontal distance. It is:
R = v^2(Sin 2A)/g
where R is range, v is velocity, A is angle, and g is the gravity constant.
we know that R=8.88 meters, A= 22.5 degrees, and g= 9.8 m/s^2
What we are looking for is v=?. We need to solve the equation for v. That gives us:
v =((R*g)/(Sin(2* 22.5)))**1/2
Next, all we have to do is plugin the values.
v = ((8.88m * 9.8 m/s**2)/(sin(2*22.5 degrees))**1/2
All this give us v = 10.11 m/s