The average rate of change from t1 to t2 where t2>t1 for a function the function H(t) is given as:
Next substitute H(t2)=110, t2=2.2, H(t1)=0, t_1=0 into the formula:
For the "b" part, substitute H(t2)=0, t2=13.2, H(t1)=198, t_1=6.6 into the formula:
The negative in the rate of change here represent a decrease in height as time increases.