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Question
primary 6 | Maths
| Speed
3 Answers Below
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Please help solve these 2 questions. Thx!
Date Posted: 4 years ago
Views: 385
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Time taken for jack: 48/80 = 36 mins
Time take for Ryan: 36+10= 46 mins
Distance for Ryan: (in hours) 46/60 x 60 = 46km
In order of Ryan to reach at the same time, he needs to cover 46km in 36mins.
36mins=36/60 hours
= 0.6hours
Average speed = 46/0.6
= 76.67km/h
Time take for Ryan: 36+10= 46 mins
Distance for Ryan: (in hours) 46/60 x 60 = 46km
In order of Ryan to reach at the same time, he needs to cover 46km in 36mins.
36mins=36/60 hours
= 0.6hours
Average speed = 46/0.6
= 76.67km/h
Thank you! Do you know the answer for qn 41 as well?
Working on it right now. Did you learn basic algebra?
Yes I did
You can also leave the answer in the exact form 76⅔ km/h
Thanks!
done
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This is the algebra way of doing it.
Date Posted:
4 years ago
You don’t have to find the speed of Ethan. After finding that Ethan needs to take D/48 + 1/6 to cover D/2 of the journey, in order for him to complete the full journey D, he needs (D/48 + 1/6) x 2 = D/24 + 1/3. Then from Daniel’s time taken which is D/24, you can conclude that Ethan needs 1/3 hour more to complete which equals to 20 mins.
Daniel was 4km ahead of Ethan when Ethan reached the halfway mark.
Since Daniel's speed was 24km/h, time he took to travel this 4km = 4km ÷ 24km/h
= 1/6 h = 10 minutes
Since Daniel took 10 minutes to travel this 4 km, this means that he actually reached the halfway mark 10 minutes before Ethan did.
So Ethan takes 10 more minutes to reach the halfway mark than Daniel.
So for the whole journey, which is twice of that distance,
Ethan will take 10min x 2 = 20 more minutes to finish it than Daniel
11.50 + 00.20 = 11.70 = 12.10
So Ethan will finish at 12.10pm
Since Daniel's speed was 24km/h, time he took to travel this 4km = 4km ÷ 24km/h
= 1/6 h = 10 minutes
Since Daniel took 10 minutes to travel this 4 km, this means that he actually reached the halfway mark 10 minutes before Ethan did.
So Ethan takes 10 more minutes to reach the halfway mark than Daniel.
So for the whole journey, which is twice of that distance,
Ethan will take 10min x 2 = 20 more minutes to finish it than Daniel
11.50 + 00.20 = 11.70 = 12.10
So Ethan will finish at 12.10pm
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