ICSE Board: Suggested Books ICSE Board: Foundation Mathematics Class 8: Reference Books Class 8: NTSE Preparation --------------------------------------------------------------

Q1. Express the following speeds in meter/sec:

Q2. Express the following speeds in km/hr:

Q3. An athlete covers a distance of 1200 meters in 4 min.48 sec. Find his speed in km/hr.

Answer:

Q4. Walking at the rate of 4 km/hr a man covers a certain distance in hours. How much time will be taken by the man to cover the same distance, if he cycles at 12 km/hr?

Answer:

Distance covered walking

Time to cover 10 km on cycle or 50 minutes

Q5. A car can finish a certain journey in 10 hours at a speed of 48 km/hr. By how much the speed of car must be increased to cover the same distance in 8 hours?

Answer:

Distance covered by the car

Speed to cover the same distance in 8 hr

Hence the speed must be increased by

Q6. A bus covers a certain distance in 50 minutes, if it runs at a speed of 54 km/hr. What must be the speed of the bus in order to reduce the time of journey to 40 minutes?

Answer:

Distance covered by the bus

Speed to cover the same distance in 40 min

Q7. A motor car starts with the speed of 70 km/hr with its speed increasing every two hours by 10 km/hr. In how much time will it cover a distance of 345 km?

Answer:

Speed at the start

Distance covered in first 2 hours

Speed After 2 hours

Distance covered in 3rd and the 4th hour

Total distance covered by end of 4th hours

Distance left to be covered after end of 4th hour

Speed After 4 hours

Time taken to cover 45 km at speed of

Hence the total time to cover

Q8. A man takes 150 steps in walking 75 meters. If he takes 3 steps in 1 second, find his speed in (i) m/sec (ii) km/hr.

Answer:

Length of one step

Distance covered in 1 sec

i) Speed in

ii) Speed in

Q9. A man walks at 5 km/hr for 6 hours and at 4 km/hr for 12 hours. Find his average speed.

Answer:

Average Speed

Average Speed

Q10. A man covers a distance of 144 km at the speed of 36 km/hr and another 256 km at the speed of 64 km/hr. Find his average speed for the whole journey.

Answer:

Average Speed

Average Speed

Q11. Two buses travel to a place at 45 km/hr and 60 km/hr respectively. If the second bus takes hours less than the first for the same journey, find the length of the journey.

Answer:

Let be the distance of the journey

Time taken by the First bus

Time taken by the Second bus

Therefore

Solving for

Q12. A boy goes to school from his village at 3km/hr and returns back at 2km/hr. If he takes 5 hours in all, what is the distance between the village and the school?

Answer:

Let be the distance of the journey

Time taken to reach school

Time taken return from

Therefore

Solving for

Q13. A bus completes a journey of 420 km in . The first ¾ part of the journey performed at 63 km/hr. Calculate the speed of the rest of the journey.

Answer:

Let be the speed of the rest of the journey

Solving for

Q14. A man drives 150 km from town A to town B in 3 hours 20 min and returns back to town A from town B in 4 hours 10 min. Find his average speed for the whole journey.

Answer:

Average Speed

Average Speed

Q15. A car completed a journey in 7 hours. One-third of the journey was performed at 20 km/hr and the rest at 30 km/hr. Find the total length of the journey.

Answer:

Let be the distance of the journey.

Solving for

Q16. A cyclist covered a certain distance in hours. The speed for first half of the distance was 15 km/hr and for the second half it was 20 km/hr. Find the total distance covered by him.

Answer:

Let be the distance of the journey.

Solving for

Q17. A person travels equal distances with speeds of 3 km/hr, 4 km/hr and 5 km/hr and takes a total time of 47 minutes. Find the total distance.

Answer:

Let be the distance of each leg

Solving for and the total distance is

Q18. A farmer traveled a distance of 61 km in 9 hours. He traveled partly on foot at 4 km/hr and partly on bicycle at 9 km/hr. Find the distance traveled by him on foot.

Answer:

Let be the distance traveled by foot

Solving for

Q19. Rohan cycles to his office at the rate of km/hr and is late by 3 minutes. However, if he travels at 15 km/hr, he reaches 5 minutes earlier than the usual time. What is the distance of his office from his residence?

Answer:

Let be the distance to office. The difference of the time in the two cases is 8 minutes.

Solving for (Distance of his office from his residency)

Q20. Robert is travelling on his cycle and has calculated to reach point A at 2 p.m. if he travels at 10 km/hr. However, he will reach there at 12 noon if he travels at 15 km/hr. At what speed must he travel to reach A at 1 p.m.?

Answer:

Let the distance traveled

Solving for

Solving for

Q21. If a train runs at 40 km/hr, it reaches its destination late by 11 minutes, but if it runs at 50 km/hr, it is late by 5 minutes only. Find the correct time for the train to complete its journey.

Answer:

Let the distance traveled by the train

Solving for (Distance of his office from his residency)

Time taken to cover 20 km=30 minutes

Therefore the correct time is 19 minutes

Q22. The distance between Delhi and Hyderabad is 1800 km. A train leaves Delhi and proceeds towards Hyderabad at a uniform speed of 60 km/hr. Another train leaves Hyderabad at the same time and proceeds towards Delhi at a uniform speed of 48 km/hr. When and where will they meet?

Answer:

Let the train meet at a distance from Delhi

Solving for . The trains will meet 1000 km from Delhi.

Time taken before them meet

ICSE Board: Suggested Books ICSE Board: Foundation Mathematics Class 8: Reference Books Class 8: NTSE Preparation --------------------------------------------------------------