Question

car moves with a steady speed of 60km/hr for 2 hours between two towns A and B. If the average speed of
the car for the round trip is 50km/hr
, then comptité the speed of the car when it moves from
to A.

Answer 1

To find the speed of the car when it moves from B to A, we can start by determining the distance between towns A and B and then use the information about the average speed for the round trip.

1. **Calculate the distance from A to B**:
- The car moves from A to B at a speed of 60 km/hr for 2 hours.
\[
\text{Distance (A to B)} = \text{Speed} \times \text{Time} = 60 \text{ km/hr} \times 2 \text{ hours} = 120 \text{ km}
\]

2. **Calculate the total distance for the round trip**:
- The total distance for the round trip (A to B and B to A) is:
\[
\text{Total Distance} = 120 \text{ km (A to B)} + 120 \text{ km (B to A)} = 240 \text{ km}
\]

3. **Calculate the total time for the round trip**:
- We know the average speed for the round trip is 50 km/hr. The formula for average speed is:
\[
\text{Average Speed} = \frac{\text{Total Distance}}{\text{Total Time}}
\]
- Rearranging for total time, we have:
\[
\text{Total Time} = \frac{\text{Total Distance}}{\text{Average Speed}} = \frac{240 \text{ km}}{50 \text{ km/hr}} = 4.8 \text{ hours}
\]

4. **Calculate the time taken for the return trip (B to A)**:
- The time taken for the trip from A to B is 2 hours. Therefore, the time for the return trip (B to A) is:
\[
\text{Time (B to A)} = \text{Total Time} - \text{Time (A to B)} = 4.8 \text{ hours} - 2 \text{ hours} = 2.8 \text{ hours}
\]

5. **Calculate the speed for the trip from B to A**:
- We can use the formula for speed:
\[
\text{Speed (B to A)} = \frac{\text{Distance (B to A)}}{\text{Time (B to A)}} = \frac{120 \text{ km}}{2.8 \text{ hours}}
\]
- Calculating this gives:
\[
\text{Speed (B to A)} \approx 42.86 \text{ km/hr}
\]

Thus, the speed of the car when it moves from B to A is approximately \(42.86 \text{ km/hr}\).