(a) (i) In first 4 minutes Mary's speed was 600 / 4 = 150 m / minute (ii) in last 4 minutes her speed was (1000-600) / 4 = 400/4 = 100 m/min (b) Marys average speed for the whole journey = 1000/8 = 125 m/min (c) 200 m (d) Peter arrived at school after 7 minutes . Mary took 8 minutes. Peter first. (e) Where they met is given by where the 2 curves intersect. That is at time 6.8 minutes and 880 m from Mary's home (f) At t= 4 dsitance between then is 600 - 400 = 200 m
