Exercise 12 (A) Question 9 - ICSE Selina Mathematic Class 6 – Idea of Speed, Distance & Time.

ICSE Selina concise maths solution

Problem 9: Jagan went to another town such that he covered 240 km by a car going at 60 h−1. Then he covered 80 km by a train, going at 100 km h−1 and the rest 200 km, he covered by a bus, going at 50 km h−1. What was his average speed during the whole journey?

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Solution

Given

Jagan covered 240 km distance by a car at 60 km/h

He travelled 80 km distance by train at 100 km/h

He travelled 200 km distance by a bus at 50 km/h

Hence,

Total distance travelled by Jagan =240km+80km+200km

=520km

Now, total time taken by during whole journey is shown below

Time taken by car =240km/60km/h

=4 hours

Time taken by a train =80km/100km/h

=4/5 hours

Time taken by bus =200km/50km/h

=4 hours

So, total time taken =4+4/5+4

=(20+4+20)/5

We get,

=44/5 hours

Hence,

Average speed = total distance / total time

=520km/(44/5) hours

=[(520×5)/44]km/h

=(130×5)/11km/h

=650/11km/h

=59111​km/h

Hence, the average speed during the whole journey is

59111​km/h