I have some conflicts with this problem as I think my teacher did it wrong.

A speeder travelling at 34m/s passes a police at rest at the side of the road. The police accelerates at 1.82m/s^2. How long does it take the policeman to catch the speeder?

He has t=6.11s while i got t=37.36.

My explanation: Since the distance travelled by both are to be equal:

vt = 0.5at^2
divide by t:
v = 0.5at
34 = 0,5(1.82)t
34 = 0.91t
t = 37.36s

I agree with your answer.