Go to navigation
It is currently Sat Nov 28, 2020 11:15 pm

All times are UTC




Post new topic Reply to topic  [ 13 posts ]  Go to page 1, 2  Next
Author Message
 Post subject: Distance question
PostPosted: Wed Jun 17, 2020 1:09 pm 
Offline

Joined: Sat Jun 30, 2018 11:46 am
Posts: 89
Hi, if anyone is able to explain how I get to this answer, I'd appreciate it please?

Four cars take part in a long distance road race. The total distance to be covered is 153 kilometers. The average speed of the cars is shown in the table below in kilometers per hour.

Car A - 96kmh
Car B - 60kmh
Car C - 108kmp
Car D - 84kmp

What distance has the slowest car in the race covered when the fastest car crosses the finish line?

A - 91KM
B - 85KM
C - 88KM
D - 95KM
E - 80KM

The answer is 85km with the explanation of: The speed of the fastest car is 108kmph. Time taken by fastest car to complete the race = 153 / 108 = 1 hours 25 min. The speed of the lowest car is 60kmph. Distance covered by the slowest car in the same time = 85km.

It's probably a simple explanation but I can't see it.

Thank you.


Last edited by ciaowood on Wed Jun 17, 2020 4:55 pm, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: Distance question
PostPosted: Wed Jun 17, 2020 3:07 pm 
Offline

Joined: Wed May 09, 2007 2:09 pm
Posts: 1201
Location: Solihull, West Midlands
You just need to remember that Speed = Distance divided by time

which means Speed x time = distance

and also time = distance divided by speed


So if you know any two of the three you can find the other (and remember to check the units, including 60 minutes in an hour! )

This triangle might help (used a lot in remembering such simple formulae)

https://owlcation.com/stem/Using-the-ma ... d-measures


Top
 Profile  
 
 Post subject: Re: Distance question
PostPosted: Wed Jun 17, 2020 3:08 pm 
Offline

Joined: Wed May 09, 2007 2:09 pm
Posts: 1201
Location: Solihull, West Midlands
(deleted to remove duplicate!)


Last edited by solimum on Wed Jun 17, 2020 3:17 pm, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: Distance question
PostPosted: Wed Jun 17, 2020 3:08 pm 
Offline

Joined: Wed Dec 05, 2018 10:16 pm
Posts: 8
As distance is speed x time. The slowest car is travelling at 60kmph or 1 km per minute
The distance the slowest car covers in 1 hour 25 mins or 85 mins will be 85km
Hope that helps


Top
 Profile  
 
 Post subject: Re: Distance question
PostPosted: Wed Jun 17, 2020 4:34 pm 
Offline

Joined: Sat Jun 30, 2018 11:46 am
Posts: 89
Thanks both, I'm clearly not familiar with this formula so I know what I'm doing tonight :lol:

Appreciate your help with this - thanks.


Top
 Profile  
 
 Post subject: Re: Distance question
PostPosted: Wed Jun 17, 2020 6:18 pm 
Offline

Joined: Sat Jun 30, 2018 11:46 am
Posts: 89
I'm struggling! I can't see how 153/108 = 1hr 25m, can anyone help please? :?


Top
 Profile  
 
 Post subject: Re: Distance question
PostPosted: Wed Jun 17, 2020 6:55 pm 
Offline

Joined: Wed May 09, 2007 2:09 pm
Posts: 1201
Location: Solihull, West Midlands
It's a bit nasty I agree, but persevere

153/108 = 1.41666667 as a decimal

Or simplifying the fraction (noticing they both are divisible by 9) = 17/12 = 1 + 5/12

1/12 of an hour is 5 minutes

So 17/12 of an hour is 1 hour plus another 25 minutes


Top
 Profile  
 
 Post subject: Re: Distance question
PostPosted: Wed Jun 17, 2020 7:54 pm 
Offline

Joined: Sat Jun 30, 2018 11:46 am
Posts: 89
Fabulously explained, thank you so much!


Top
 Profile  
 
 Post subject: Re: Distance question
PostPosted: Wed Jun 17, 2020 10:46 pm 
Offline

Joined: Mon Feb 12, 2007 1:21 pm
Posts: 16238
This is not an appropriate 11+ question.


Top
 Profile  
 
 Post subject: Re: Distance question
PostPosted: Wed Jun 17, 2020 10:47 pm 
Offline

Joined: Mon Feb 12, 2007 1:21 pm
Posts: 16238
solimum wrote:

This triangle might help (used a lot in remembering such simple formulae)

https://owlcation.com/stem/Using-the-ma ... d-measures


NEVER teach this to children please.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 13 posts ]  Go to page 1, 2  Next

All times are UTC


Who is online

Users browsing this forum: No registered users and 5 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Privacy Policy | Refund Policy | Disclaimer | Copyright © 2004 – 2020