A car travels a certain distance taking 7 hrs in forward journey, during the return journey increased speed 12km/hr takes the times 5 hrs.What is the distance travelled?
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110
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240
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210
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100
Let distance be d km. Forward speed = d/7 km/hr. Return speed = d/5 km/hr. Given return speed is 12 km/hr faster: d/5 - d/7 = 12. Solving: 7d - 5d = 420, 2d = 420, d = 210 km. Verification: Forward speed = 30 km/hr, return speed = 42 km/hr (12 km/hr faster ✓).
To solve this question, we can use the formula:
Distance = Speed x Time
Let's assume the initial speed of the car during the forward journey is "x" km/hr.
According to the given information, the car takes 7 hours to travel a certain distance during the forward journey, so we can write the equation as:
Distance = x km/hr * 7 hrs
Now, during the return journey, the speed of the car is increased by 12 km/hr, so the speed becomes "x + 12" km/hr. The car takes 5 hours to travel the same distance during the return journey, so we can write the equation as:
Distance = (x + 12) km/hr * 5 hrs
Since the distance travelled is the same in both cases, we can equate the two equations:
x km/hr * 7 hrs = (x + 12) km/hr * 5 hrs
Simplifying this equation, we get:
7x = 5(x + 12)
Now, solve for x:
7x = 5x + 60 2x = 60 x = 30
So, the initial speed of the car during the forward journey is 30 km/hr.
Now, we can calculate the distance travelled using the forward journey equation:
Distance = x km/hr * 7 hrs Distance = 30 km/hr * 7 hrs Distance = 210 km
Therefore, the correct answer is option C) 210 km.