physics
posted by shaknocka .
A speedboat starts from rest and accelerates at +1.69 m/s2 for 7.18 s. At the end of this time, the boat continues for an additional 4.55 s with an acceleration of +0.468 m/s2. Following this, the boat accelerates at 0.657 m/s2 for 8.38 s. (a) What is the velocity of the boat at t = 20.11 s? (b) Find the total displacement of the boat.

V1 = 1.69m/s^2 * 7.18s = 12.13m/s.
V2 = 0.468m/s^2 * 4.55s = 2.13m/s.
V3 = 0.657m/s^2 * 8.38s = 5.51m/s.
a. V = V1 + V2 + V3 = 12.13 + 2.13  5.51 = 8.75m/s at 20.11s. 
i got the right answer right for acceleration ... to find the total displacement i did 8.75 times 20.11 but its not the right answer