A' goes 10 km.distance with average speed of 6km/hr while rest 20 km he travels with an average speed of 15km/hr.What is the average speed of 'A' during the whole journey?

Options

A. 10 km/h
B. 12 km/h
C. 13 km/h
D. 14.5 km/h

Answer

To find the average speed of 'A' during the whole journey, we can follow these steps:

### Step 1: Calculate the time taken for the first part of the journey.
- Distance = 10 km
- Speed = 6 km/hr
- Time = Distance / Speed = 10 km / 6 km/hr = 5/3 hours (or approximately 1.67 hours)

### Step 2: Calculate the time taken for the second part of the journey.
- Distance = 20 km
- Speed = 15 km/hr
- Time = Distance / Speed = 20 km / 15 km/hr = 4/3 hours (or approximately 1.33 hours)

### Step 3: Calculate the total time taken for the journey.
- Total Time = Time for first part + Time for second part
- Total Time = (5/3) hours + (4/3) hours = (5 + 4) / 3 = 9/3 hours = 3 hours

### Step 4: Calculate the total distance covered during the journey.
- Total Distance = Distance of first part + Distance of second part
- Total Distance = 10 km + 20 km = 30 km

### Step 5: Calculate the average speed for the whole journey.
- Average Speed = Total Distance / Total Time
- Average Speed = 30 km / 3 hours = 10 km/hr

Thus, the average speed of 'A' during the whole journey is **10 km/hr**.

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