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Question
Jagan went to another town such that he covered 240 km by a car going at 60 kmh-1. Then he covered 80 km by a train, going at 100 kmh-1 and the rest 200 km, he covered by a bus, going at 50 kmh-1. What was his average speed during the whole journey?
Solution
Distance covered 240 km by car with speed 60 km/h
Distance covered 80 km by train with speed 100 km/h
and rest distance covered 200 km by bus with speed 50 km/h
Total distance covered = (240 + 80 + 200) km = 520 km
Now time taken by car = `240/60` = 4 hours
Time taken by train = `80/100=4/5` hours
and time taken by bus = `200/50` = 4 hours
∴ Total time taken
= `4+4/5+4=8 4/5=44/5` hours
∴ Average speed
= `"Distance"/"Time"=520/(44/5)=(520xx5)/44` km/h
= `650/11=59 1/11` km/h
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