Question

7. A man walked 12km at 3km/hr and cycle 18km at 9km/hr. what is his average speed for the whole journey? 8. A runny boy has a speed of 4.5m/s, if he up for 15 sec. how far will he travelled?​

Answer 1

The man's average speed for the whole journey is 5 km/hr. The running boy will travel a distance of 67.5 meters in 15 seconds.

Step-by-step explanation:

Calculation of Average Speed

For the man who walked and cycled, we calculate his average speed by dividing the total distance by the total time taken for his journey.

Total distance = distance walked + distance cycled

= 12 km + 18 km

= 30 km.

To find the total time taken, we divide the distances by the speeds and add them up:

Time walking = distance/speed

= 12 km / 3 km/hr

= 4 hours.

Time cycling = distance/speed

= 18 km / 9 km/hr

= 2 hours.

Total time = time walking + time cycling

= 4 hours + 2 hours

= 6 hours.

Now, average speed = total distance / total time

= 30 km / 6 hours

= 5 km/hr.

Distance Traveled by Running Boy

For the running boy, to find how far he travels in 15 seconds:

Distance = speed x time

= 4.5 m/s x 15 s

= 67.5 meters.