3. You drive on NH-4 from New Delhi to Agra, half the time at 55 km/h and the other half at 90 km/h. On the way back you travel half the distance at 55 km/h and the other half at 90 km/h. What is your average speed (a) from New Delhi to Agra, (b) from Agra to New Delhi, (c) for the entire trip? (d) What is your average velocity for the entire trip?