Question

sample sums on speed ​

Answer 1

Explanation:

Illustration 5: A train covered first 120 km at a speed of 20 km an hour and then covered the remaining 180 km at a speed of 45 km an hour. Find its average speed.

Sol: Total distance = 120 + 180 = 300 km. Time taken for the first 120 km = 120/20 → 6 hrs.

Time taken for the next 180 km = 180/45 → 4 hrs. Total time taken = 6 + 4 = 10 hrs.

Average Speed =Total Distance Travelled/Total Time Taken = 300/10 = 30 km/hr.

Illustration 6: A cyclist travels at 10 km/hr for 2 hours and then at 13 km/hr for 1 hour. Find his average speed.

Sol: Distance travelled in first 2 hours =10 × 2 = 20 km. Distance travelled in next 1 hour =13 × 1 = 13 km. Total Distance travelled = 20 + 13 = 33 km. Total time taken = 2 + 1 = 3 hrs.

Average Speed =Total Distance Travelled/Total Time Taken =33/3 = 11 km/hr.

Type 3. Average Speed: When the time travelled is the same:The average speed of traveling at two different speeds for the same time span is just the simple average of these two speeds.

Illustration 7: A motorist travels one hour at an average speed of 45 kmph and the next hour at an average speed of 65 kmph. Then what is his average speed?

Sol: (45 + 65) ÷ 2 = 55 kmph. The total distance traveled by the motorist in these two hours = 65 + 45 = 110 km and he has taken two hours. Therefore, his average speed = 55 kmph.

Answer 2

1. If it takes 3 hours to drive a distance of 192km on a motorway, what would be your average speed in km/h?

2. What is your average speed in mph if you travel 15 miles in 2 hours and 30 minutes?

3. John decided to cycle to his friend’s house at a speed of 5km/h and the journey took 2 hours. How far did John cycle?.

4. As another example, Sally runs at a pace of 8km/h. If she ran for a period of four hours, how far has she travelled?