Multiple choice

The distance between station A and B by road is 240 km and by train it is 300 km. A car starts from station A with a speed of x km/hr whereas a train starts from station B with a speed 20 km/hr more than the speed of the car. If the time taken by train is 1 hour less than that taken by the car, the speed of the car is:

  1. 60 km/hr

  2. 120 km/hr

  3. 40 km/hr

  4. 80 km/hr
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The time taken by the car is 240/x hours, and the time taken by the train is 300/(x + 20) hours. We are given that the train's time is 1 hour less than the car's time, so 240/x - 300/(x + 20) = 1. Solving this equation or testing the options gives x = 40 km/hr.

AI explanation

From the quadratic equation x squared + 80x minus 4800 equals 0, we factor the equation to find the roots. The equation factors into (x + 120)(x minus 40) equals 0. Since the speed cannot be negative, the speed of the car is 40 km/hr.

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