| Two cities A and B are 360 km apart. A car goes from A to B with a speed of 40 km/h and returns to A with a speed of 60 km/h. What is the average speed of the car? |
A) 45 km/h
B) 48 km/h
C) 50 km/h
D) 55 km/h
Correct Answer: B
Solution :
| Distance between the cities A and B = 360 km |
| \[\therefore \] Average speed \[=\frac{\text{Total}\,\,\text{distance}\,\,\text{covered}}{\text{Total}\,\text{time}\,\text{taken}}\] |
| \[=\frac{360+360}{\frac{360}{40}+\frac{360}{60}}=\frac{720}{9+6}\] |
| \[=\frac{720}{15}=48\,\,km/h\] |
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