Answer:
a = 0.264 [m/s^2]
Step-by-step explanation:
We can find the deceleration value using the following formula of kinematics:

The final speed is taken as zero as the rider stops completely and the acceleration sign in the equation is taken as negative as the rider is slowing down.
Vf = final velocity = 0
Vo = initial velocity = 4.6 [m/s]
t = time = 0.29 [min] = 0.29*60 = 17.4 [s]
0 = 4.6 - (a*17.4)
-4.6 = - 17.4*a
a = 0.264 [m/s^2]