In order to determine the average force the wall exerted on the ball, use the following formula:

where
Δp: change in momentum
Δt: change in time = 45 ms = 0.045 s
F: force = ?
calculate the change in momentum as follow:

next, replace Δp and Δt into the formula for F:

Hence, the average force exterded by the wall on the ball was approximately 216.67N