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primary 6 | Maths
| Speed
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Date Posted: 4 years ago
Views: 542
1h 20 min = 1 20/60 h = 1⅓ h
Distance travelled for the first part
= 1⅓h x 60km/h
= 80km
So the distance of ¼ of his journey is 80km.
Since 1 - ¼ = ¾, he has ¾ of the distance left to travel.
¾ of journey = 80km x 3 = 240km
As he has to complete the journey in 4h,
4h - 1⅓h = 2⅔h
He has 2⅔h left to travel the remaining 240km.
His average speed has to be :
240km ÷ 2⅔h = 90km/h
(In your working, you can convert 1⅓h to 4/3 h and 2⅔h to 8/3 h, then cross out the denominator by dividing the numerator of the 60km and 240km respectively, if you want to show working without using calculator.)
Distance travelled for the first part
= 1⅓h x 60km/h
= 80km
So the distance of ¼ of his journey is 80km.
Since 1 - ¼ = ¾, he has ¾ of the distance left to travel.
¾ of journey = 80km x 3 = 240km
As he has to complete the journey in 4h,
4h - 1⅓h = 2⅔h
He has 2⅔h left to travel the remaining 240km.
His average speed has to be :
240km ÷ 2⅔h = 90km/h
(In your working, you can convert 1⅓h to 4/3 h and 2⅔h to 8/3 h, then cross out the denominator by dividing the numerator of the 60km and 240km respectively, if you want to show working without using calculator.)
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90km/h
Date Posted:
4 years ago
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