Question

Jeff takes 20 mins to jog around the race course one time. And 25 mins to jog arpund second time. What is his average speed in kms per hr fpr the whole jog if the course is 3 kms long?

Answer 1

The main formula used in work-rate, distance-speed problems is:

Work=Rate*Time, or Distance=Speed*Time.


Thus, the time is: $speed= \frac{distance}{time}$.


In our problem, the total distance is 3 km + 3 km = 6 km.

the total time is 20 min + 25 min = 45 min.

60 minutes are 1 hour, then 

45 minutes are $\frac{45min*1h}{60min}= 0.75h$


Thus, the average speed is : distance/time = 6 km/ 0.75 h = 8 km/h


Answer: 8 km/h