
By: doreenJ (offline) Thursday, May 16 2013 @ 06:31 AM CDT (Read 1444 times)



doreenJ 
Jim is preparing for his triathlon. Last Sunday, he cycled at a uniform speed 15 km/h to a park. He cycled at a uniform speed of 12 km/h for his return trip. What was his average speed for the whole trip? ( Give your answer in fraction.)
Please help!

Newbie
Registered: 11/08/11 Posts: 3





By: echeewh (offline) Thursday, May 16 2013 @ 08:44 AM CDT



echeewh 
Hi Doreen,
//
19May: Updated
My sincere apologies for overlooking that. Apparently the answerkey of 13 1/3 km/h is correct.
Many thanks to <aceacademy> and <jo sarah> for pointing that out. Pls refer to solution presented by <aceacademy>
//
I guess why you asked this is because the <answerkey> turns out to be 13 1/3 km/h. Am I correct?
If your answer is 13 1/2 km/h instead, then I think you should feel good about it .
Hope this helps.
Cheers,
Edward

Active Member
Registered: 04/21/11 Posts: 627





By: doreenJ (offline) Thursday, May 16 2013 @ 09:45 AM CDT



doreenJ 
Thanks Edward , I got the answer 13 1/2 km/h.

Newbie
Registered: 11/08/11 Posts: 3





By: aceacademy (offline) Saturday, May 18 2013 @ 12:25 AM CDT



aceacademy 
Hi,
13 1/3 km/h is the correct answer.
Working:
Assuming the park is 15km away.
Trip to park took 1h.
Return trip took (15/12)h = 1.25h.
Total distance = 30km
Total time taken = 2.25h
Ave speed for whole trip = (30 / 2.25) km/h = 13 1/3 km/h.
Hope this helps.

Regular Member
Registered: 03/26/13 Posts: 88





By: jo sarah (offline) Saturday, May 18 2013 @ 09:15 AM CDT



jo sarah 
the correct answer is 13 1/3, not 13 1/2.
Remember: average speed is Total distance divide by Total time.

Regular Member
Registered: 03/20/12 Posts: 111





By: echeewh (offline) Saturday, May 18 2013 @ 01:37 PM CDT



echeewh 
Hey Doreen,
My sincere apologies for overlooking that. Apparently the answerkey of 13 1/3 km/h is correct.
Many thanks to <aceacademy> and <jo sarah>.
Best regards,
Edward

Active Member
Registered: 04/21/11 Posts: 627



