A rocket carrying a satellite is accelerating

A rocket carrying a satellite is accelerating straight up from the earth’s surface. At 1.15 s after liftoff, the rocket clears the top of its launch platform, 63 m above the ground. After an additional 4.75 s, it is 1.00 km above the ground. Calculate the magnitude of the average velocity of the rocket for

(a) The 4.75-s part of its flight and

(b) The first 5.90 s of its flight.