Suppose that the position vector for a particle is given as a function of time by vector r (t) = x(t)î + y(t)ĵ, with x(t) = at + b and y(t) = ct2 + d, where a = 1.30 m/s, b = 1.45 m, c = 0.129 m/s2, and d = 1.16 m. (a) calculate the average velocity during the time interval from t = 2.05 s to t = 4.25 s.