Answer:
[tex]average\ speed = 36\ mi/hr[/tex]
Step-by-step explanation:
Given:
Each city is exactly 120 miles from the other two.
Average rate from city A to city B = 60 mi/hr
Average rate from city B to city C = 40 mi/hr
Average rate from city c to city A = 24 mi/hr
We need to find the Dale's average rate for the entire trip.
Solution:
First we find the total time and total distance by following way.
Time taken to travel from A to B = [tex]\frac{Distance}{Speed} = \frac{120}{60}= 2\ hr[/tex]
Time taken to travel from B to C = [tex]\frac{Distance}{Speed} = \frac{120}{40}= 3\ hr[/tex]
Time taken to travel from C to A = [tex]\frac{Distance}{Speed} = \frac{120}{24}= 5\ hr[/tex]
So, total time taken = [tex]2+3+5=10\ hr[/tex]
Total distance = 120 + 120 + 120 = 360 miles
Using average speed formula.
[tex]average\ speed = \frac{Total\ distance}{Total\ time\ taken}[/tex]
[tex]average\ speed = \frac{360}{10}[/tex]
[tex]average\ speed = 36\ mi/hr[/tex]
Therefore, the average rate for the entire trip [tex]average\ speed = 36\ mi/hr[/tex]
