Kelly walks to school. She walks 600m at a constant rate for 3 minutes. She sees a friend who she stops to talk to for 2 minutes. She continues to walk the remaining 500 m in 5 minutes while increasing her speed until she reaches the school.

b) Calculate the average speed at which she walked between 5 and 10 minutes.

c) Calculate her instantaneous rate of change at exactly 2 minutes.

d) Calculate her instantaneous velocity at exactly 4 minutes.