Soh's answer to Xingyao's Primary 6 Maths Speed Singapore question.
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Date Posted:
4 years ago
Answer should be 8hrs.
When car started 2hrs later, lorry already 2x60 =120 km AHEAD.
This means car need to catch up a distance of 120km.
Difference in speed to 75-60 = 15km/hr. This means that car catches up with lorry a distance of 15km every hour.
Therefore 15km in 1 hr.
120km in 120/15 = 8 hrs. (answer)
When car started 2hrs later, lorry already 2x60 =120 km AHEAD.
This means car need to catch up a distance of 120km.
Difference in speed to 75-60 = 15km/hr. This means that car catches up with lorry a distance of 15km every hour.
Therefore 15km in 1 hr.
120km in 120/15 = 8 hrs. (answer)
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