Answer:
The car's average speed is 16 feet per second.
Explanation:
The expression for the average speed is as follows;
[tex] A.S=\frac{\textrm{Total distance}}{\textrm{total time}}[/tex]
Given expression of distance:
[tex]d=t^{2}+5t[/tex]
Put t= 4 s.
[tex]d(4)=(4)^{2}+5(4)[/tex]
d(4)= 36 ft
Put t= 7 s in the given expression.
[tex]d(7)=(7)^{2}+5(7)[/tex]
d(7)= 84 ft
Calculate the car's average speed over the interval of time from t = 4 seconds to t = 7 seconds.
[tex]A.S=\frac{d(7)-d(4)}{7-4}[/tex]
[tex]A.S=\frac{84-36}{7-4}[/tex]
A.S= 16 feet per second
Therefore, the car's average speed is 16 feet per second.
