A cyclist travels the first kilometer at a rate of 10 km per hour, the second kilometer at a rate of 3 km per hour, and the third kilometer at a rate of 6 km per hour. Find the average speed of the cyclist.



Answer :

To find the average speed of the cyclist over the entire journey, we need to follow a step-by-step process. Here's how we do it:

1. Determine the times taken for each kilometer:
- The time taken to travel the first kilometer at a speed of 10 km/hr:
[tex]\[ \text{Time for 1st km} = \frac{1 \, \text{km}}{10 \, \text{km/hr}} = 0.1 \, \text{hours} \][/tex]
- The time taken to travel the second kilometer at a speed of 3 km/hr:
[tex]\[ \text{Time for 2nd km} = \frac{1 \, \text{km}}{3 \, \text{km/hr}} = 0.333\ldots \, \text{hours} \approx 0.333 \][/tex]
- The time taken to travel the third kilometer at a speed of 6 km/hr:
[tex]\[ \text{Time for 3rd km} = \frac{1 \, \text{km}}{6 \, \text{km/hr}} = 0.166\ldots \, \text{hours} \approx 0.167 \][/tex]

2. Calculate the total distance traveled:
- The cyclist travels a total distance of 3 kilometers:
[tex]\[ \text{Total distance} = 1 \, \text{km} + 1 \, \text{km} + 1 \, \text{km} = 3 \, \text{km} \][/tex]

3. Calculate the total time taken for the journey:
- Adding up the time taken for each segment:
[tex]\[ \text{Total time} = 0.1 \, \text{hours} + 0.333 \, \text{hours} + 0.167 \, \text{hours} = 0.6 \, \text{hours} \][/tex]

4. Calculate the average speed:
- Average speed is given by the total distance divided by the total time:
[tex]\[ \text{Average speed} = \frac{\text{Total distance}}{\text{Total time}} = \frac{3 \, \text{km}}{0.6 \, \text{hours}} = 5 \, \text{km/hr} \][/tex]

Therefore, the average speed of the cyclist over the entire journey is [tex]\(5 \, \text{km/hr}\)[/tex].