A particle is moving in three dimensions and its position vector is given by; r(t) = (4, 4t + 2, 3t)i + (4, 5t - 2, 3)2 + (3, 3t + 3, 1t)k where r is in meters and t is in seconds. Determine the magnitude of the average acceleration between t=1s and t 3s. Express your answer in units of m/s2 using one decimal place.