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Read also the posting on Sarin learns rate of change in school (Math Concept) to learn about concept of speed.
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Upper primary school mathematics question UPQ283
The travel distance from Simei Town to JB Town was 375 km apart. Sarin’s father left Simei Town for JB Town to visit his friend at 10 am traveling at an average speed of 75 km/h. A taxi left Simei Town some time later than Sarin’s father and overtook him at 12 noon. The taxi travelled at an average speed of 90 km/h.
(a) At what time did the Taxi leave Simei Town?
(b) How much later did Sarin’s father arrive in JB Town than the taxi?
From 10 am to 12 noon,
Sarin’s father travelled in this 2 hours = 75 × 2 = 150 km
The Taxi was travelled at 90 km/h
The time required for Taxi to travel the 150 km = 150 ÷ 90 = 1 2/3 h = 1 h 40 min
The taxi left Simei Town at 10.20 am
The distance from both of them met to JB Town = 375 – 150 = 225km
The time needed for taxi to travel 225 km = 225 ÷ 90 = 2.5 h
The time needed fro Sarin’s father to travel 225km = 225 ÷ 75 = 3 h
Sarin’s father arrive in JB town later than the taxi by 3 – 2.5 = 0.5 h