Multiple choice

Pankaj travelled a certain part of the journey with speed 5 km/h and then he took an auto travelling at 25 km/h for the remaining part of the journey. He took 10 hours for the entire journey. What distance did he travelled by auto if the average speed of the entire journey be 17 km/h.

  1. 750 km

  2. 100 km

  3. 150 km

  4. 200 km

  5. 250 km
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

With an average speed of 17 km/h over 10 hours, the total distance travelled is 170 km. Let t be the time spent in the auto; then the time spent walking is 10 - t. Solving the distance equation 5*(10 - t) + 25*t = 170 gives 20*t = 120, so t = 6 hours, and the distance by auto is 25 * 6 = 150 km.

AI explanation

The total distance of the journey is calculated by multiplying the average speed by the total time, giving 17 multiplied by 10 equals 170 km. Let the time spent walking be t hours, so the time in the auto is 10 minus t. Using the formula distance equals speed multiplied by time, we get 5t + 25(10 minus t) equals 170. Solving this gives t equals 4 hours, meaning he spent 6 hours in the auto, so the distance traveled by auto is 25 multiplied by 6 equals 150 km.

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