Answer: 1224 miles
Step-by-step explanation:
Given
the average speed of a person is 51 mph
If speed is increased to 72 mph, he would have reached 7 hr earlier
Suppose d and t be the distance and time taken
[tex]\Rightarrow t_1=\dfrac{d}{51}[/tex]
If the speed is 72 mph
[tex]\Rightarrow t_2=\dfrac{d}{72}[/tex]
Also, [tex]t_1-t_2=7[/tex]
[tex]\Rightarrow \dfrac{d}{51}-\dfrac{d}{72}=7\\\\\Rightarrow \dfrac{1}{51}-\dfrac{1}{72}=\dfrac{7}{d}\\\\\Rightarrow \dfrac{24-17}{1224}=\dfrac{7}{d}\\\\\Rightarrow \dfrac{7}{1224}=\dfrac{7}{d}\\\\\Rightarrow d=1224\ miles[/tex]
