A driver can stop his car from the red signal at a distance 20m when 36km/hr and 41.25 m when speed is 54km/hr then the reaction time is ?

I think so the answer is 1.5 sec. Because reaction time here is the difference in the time taken to stop the vehicle. Case 1: u is 10m/s since v=0 u=at=10 applying this in 3rd equation of motion v^2-u^2=2as and substituting for a as t/10 we get t as 4 sec when the same is done for 2nd case we get t as 5.5 sec The absolute difference of both is 1.5sec