A bicycle traveling at 9.8 m/s needs to stop in a time of 5s. what coefficient of friction is required?

Answer:0.2, can someone possibly show me how this is the answer? i keep getting something else.

a = 9.8 m/s / 5 s

f = m a = m g μ

a = g μ

9.8 m/s / 5 s = 9.8 m/s^2 * μ