Page 149 - Maths Skills - 8

Direct and Inverse Proportions 147

Exercise 9.5

1. Express in km/h.
(i) 25 m/s (ii) 60 m/s (iii) 45 m/s (iv) 65 m/s
2. Express in m/s.

(i) 9 km/h (ii) 36 km/h (iii) 90 km/h (iv) 144 km/h
3. A cyclist cycles at 21 km/h. How long will he take to cover a distance of 700 metres?

4. A train, 80 m long, is moving at 80 km/h. If it takes 18 seconds to cross a bridge, then find the length
of the bridge.
5. A bus travels at a speed of 45 km/h. How much distance does it cover in 18 seconds?
6. A train 335 m in length crosses a man, standing on a platform, in 20 seconds. Find the speed of the train.
How long will it take to pass a platform of length 201 m?

7. The speed of a jeep is 125 km/h. It takes 120 minutes to cover a certain distance. Find the distance
in metres.
8. The speed of a flying bird is 5 km/h. If it flies non-stop, how long will it take to cover a distance of
3500 metres?

9. A gun is fired from a point 6.64 km away from Suresh. He hears the sound 20 seconds later. Find the
speed of the sound.

10. How long will Meera take to run around a circular field of circumference 45 m, if she runs at the rate of
9 km/h?
11. A cyclist travels at a speed of 25 km/h over a certain distance and then returns over the same distance
at a speed of 15 km/h. What is his speed for the total journey?
12. Seema reaches the school early by 10 minutes if she cycles at a speed of 12 km/h, but reaches the school
late by 5 minutes, if she cycles at 9 km/h. Find the distance of the school from her home.

13. Sound travels at the speed of 330 m/s. How many kilometres will it travel in two hours?
14. A train covers a distance of 360 km in 6 hours. By how much should the speed be increased to cover the
same distance in 4 hours?

15. A 560 m long train is moving at 72 km/h. In what time will it cross a tree?
16. A car is moving at a speed of 78 km/h. What time will it take to cover 650 metre?
17. Rajdhani Express reaches Delhi from Bhubaneshwar with an average speed of 120 km/h in 15 hours.
Find the distance between Delhi and Bhubaneshwar.

18. Two trains, 120 m and 80 m long are moving on parallel tracks in the same direction with speeds of
31 km/h and 23 km/h respectively. How long will it take the train with speed of 31 km/h to cross
the other?