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primary 6 | Maths
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May I know the answer is 100m or 120m? Thank you.
Date Posted: 4 years ago
Views: 302
120m
Thank you.
Welcome.
Do take note that there is actually no need to assume the time taken for Andy completed the race.
In fact I would recommend not to do so as it can get confusing on what time to decide to assume. And this will not work for all questions.
My approach :
When Andy finished the 600m race,
Ben had only finished 500m and Chris had only travelled 400m, all in the same time.
So Ben has 100 m more to go. That's 1/5 of his previous distance travelled , so he will need 1/5 of the previous time taken to complete this 100m to finish the race.
Now, while Ben was travelling this last 100 m, Chris would have also been travelling.
So his distance travelled is 1/5 of his previous distance too since the time that passed here was also 1/5 of the previous time taken.
1/5 x 400m = 80m
He would have only travelled 80m in the same time that Ben travelled 100m to finish the race.
Now Chris had 200m to go when Andy finished. So now having travelled another 80m,
200m - 80m = 120m
He would have 120m left and thus be 120m away from finishing line when Ben finished.
Do take note that there is actually no need to assume the time taken for Andy completed the race.
In fact I would recommend not to do so as it can get confusing on what time to decide to assume. And this will not work for all questions.
My approach :
When Andy finished the 600m race,
Ben had only finished 500m and Chris had only travelled 400m, all in the same time.
So Ben has 100 m more to go. That's 1/5 of his previous distance travelled , so he will need 1/5 of the previous time taken to complete this 100m to finish the race.
Now, while Ben was travelling this last 100 m, Chris would have also been travelling.
So his distance travelled is 1/5 of his previous distance too since the time that passed here was also 1/5 of the previous time taken.
1/5 x 400m = 80m
He would have only travelled 80m in the same time that Ben travelled 100m to finish the race.
Now Chris had 200m to go when Andy finished. So now having travelled another 80m,
200m - 80m = 120m
He would have 120m left and thus be 120m away from finishing line when Ben finished.
Noted with thanks.
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Sometimes, Assumption is needed to better Understand a Question;)
Date Posted:
4 years ago
Thank you
May I know the 6sec is assume because not given? Thank you.
Yup. The 6 seconds is an assumption. You can try 10 seconds or any number. Answers will be the same eventually. Remember to be consistent for the 3 students. If you use 10 seconds, 10 seconds for Andy to cover 600m, 10 seconds for Ben to cover 500m and 10 seconds for Chris to cover 400m ;)
Thank you very much.
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