A car travels a distance of 75km at the speed of 25km/h.It covers the next 25 km of its journey at the speed of 5km/h and the last 50 km of its journey at the speed of 25km/h. What is the average speed of the car?

Options

A. 40 km/h
B. 25 km/h
C. 15 km/h
D. 12.5 km/h

Answer

To find the average speed of the car, we need to follow these steps:

### Step 1: Calculate Total Distance
The car travels three segments:
1. First segment: 75 km
2. Second segment: 25 km
3. Third segment: 50 km

**Total Distance = 75 km + 25 km + 50 km = 150 km**

### Step 2: Calculate Time for Each Segment
We will calculate the time taken for each segment using the formula:
\[ \text{Time} = \frac{\text{Distance}}{\text{Speed}} \]

1. **First segment:**
- Distance = 75 km
- Speed = 25 km/h
- Time = \( \frac{75}{25} = 3 \) hours

2. **Second segment:**
- Distance = 25 km
- Speed = 5 km/h
- Time = \( \frac{25}{5} = 5 \) hours

3. **Third segment:**
- Distance = 50 km
- Speed = 25 km/h
- Time = \( \frac{50}{25} = 2 \) hours

### Step 3: Calculate Total Time
Now, we add the time taken for each segment:
\[ \text{Total Time} = 3 \text{ hours} + 5 \text{ hours} + 2 \text{ hours} = 10 \text{ hours} \]

### Step 4: Calculate Average Speed
The average speed is given by the formula:
\[ \text{Average Speed} = \frac{\text{Total Distance}}{\text{Total Time}} \]

Substituting the values we calculated:
\[ \text{Average Speed} = \frac{150 \text{ km}}{10 \text{ hours}} = 15 \text{ km/h} \]

### Conclusion
The average speed of the car is **15 km/h**.

---