A man run a distance of 9km/hr for a distance of 4km.And 2km/hr for the rest of the distance.The whole run takes him 1hour.his average speed for the first distance in 4km is?
since time = distance/speed,
4/9 + x/2 = 1
That will tell you the rest of the distance.
I suspect you have garbled your question, since they told you his speed for the first 4km was 9km/hr.
To find the average speed for the first distance of 4 km, we need to use the formula:
Average speed = Total distance / Total time
We are given that the man runs at a speed of 9 km/hr for the first distance of 4 km and at a speed of 2 km/hr for the remaining distance.
Let's start by finding the time taken to cover the first distance of 4 km:
Time = Distance / Speed = 4 km / 9 km/hr
Next, let's find the time taken to cover the remaining distance:
Time = Distance / Speed = (Total distance - First distance) / Speed = (4 km - 4 km) / 2 km/hr = 0 hr
Since the man covers the remaining distance of 0 km in 0 hours, it doesn't contribute to the total time.
Now, let's calculate the total time taken by adding the time taken for the first distance and the remaining distance:
Total time = Time taken for the first distance + Time taken for the remaining distance = (4 km / 9 km/hr) + 0 hr = 4/9 hr
Finally, substitute the values into the average speed formula:
Average speed = Total distance / Total time = 4 km / (4/9) hr
To simplify this, we can multiply the numerator and denominator by the reciprocal of the denominator:
Average speed = 4 km * (9/4) / 1 hr = 9 km/hr
Therefore, the average speed for the first distance of 4 km is 9 km/hr.