Exercise 12 (B) Question 9 - Selina Mathematic Class 6 – Idea of Speed

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

Problem 9: A boy swims 200m in still water and then returns back to the point of start in total 10 minutes. Find the speed of his swim in metres per second.

Distance swimmed by boy of =200+200=400m

Time taken=10 minutes

∴speed=10×60400​=32​m/s

Problem 9: A boy swims 200 m in still water and then returns back to the point of start in total 10 minutes. Find the speed of his swim in kmh^{-1}

A boy swims 200 m in still water and then returns back to the starting point in total 10 minutes

So,

Distance=200m+200m

=400m

Time=10minutes

Hence,

Speed=400/10

=40 m/min

Now, converting into km/h, we get

=(40×60)/1000km/h

We get,

=24/10km/h

=2.4km/h

Therefore, the speed of the boy swim in kilometer per hour is 2.4km/h