If a 1500 kg car can accelerate from 35 km/h to 55 km/h in 3.2 s, how long will it take to accelerate from 55 km/h to 100 km/h? assume the power stays the same, and neglect frictional losses

The question above can be answered by using the equation below,
                                    PΔt = 1/2 (mv²)
From the first case, we solve the power.
                             P(3.2s) = 0.5(1500)(55² - 35²)
This gives us a value of P which is 421875. 
Using this same power to solve for t in the second scenario,
                                      421875 *t = 0.5(1500)(100²-55²)
The value of t is 12.4 s.