Distance question
Moderators: Section Moderators, Forum Moderators
Distance question
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.
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 5:55 pm, edited 1 time in total.
Re: Distance question
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" onclick="window.open(this.href);return false;
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" onclick="window.open(this.href);return false;
Re: Distance question
(deleted to remove duplicate!)
Last edited by solimum on Wed Jun 17, 2020 4:17 pm, edited 1 time in total.
-
- Posts: 8
- Joined: Wed Dec 05, 2018 11:16 pm
Re: Distance question
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
The distance the slowest car covers in 1 hour 25 mins or 85 mins will be 85km
Hope that helps
Re: Distance question
Thanks both, I'm clearly not familiar with this formula so I know what I'm doing tonight
Appreciate your help with this - thanks.
Appreciate your help with this - thanks.
Re: Distance question
I'm struggling! I can't see how 153/108 = 1hr 25m, can anyone help please?
Re: Distance question
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
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
Re: Distance question
Fabulously explained, thank you so much!
Re: Distance question
This is not an appropriate 11+ question.
Re: Distance question
NEVER teach this to children please.solimum wrote:
This triangle might help (used a lot in remembering such simple formulae)
https://owlcation.com/stem/Using-the-ma ... d-measures" onclick="window.open(this.href);return false;