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.
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Calculate the distance from A to B:
- The car moves from A to B at a speed of 60 km/hr for 2 hours. \[ \text{Distance (A to B)} = \text{Speed} \times \text{Time} = 60 \text{ km/hr} \times 2 \text{ hours} = 120 \text{ km} \]
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Calculate the total distance for the round trip:
- The total distance for the round trip (A to B and B to A) is: \[ \text{Total Distance} = 120 \text{ km (A to B)} + 120 \text{ km (B to A)} = 240 \text{ km} \]
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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: \[ \text{Total Time} = \frac{\text{Total Distance}}{\text{Average Speed}} = \frac{240 \text{ km}}{50 \text{ km/hr}} = 4.8 \text{ hours} \]
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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: \[ \text{Time (B to A)} = \text{Total Time} - \text{Time (A to B)} = 4.8 \text{ hours} - 2 \text{ hours} = 2.8 \text{ hours} \]
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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 \(42.86 \text{ km/hr}\).
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