Multiple choice

The total distance between two stations is $570$ km out of which , $224$ km is covered at $56$ km/hr, $210$ km is covered at $70$ km/hr and remaining is covered in $2$ hours. Find the average speed during the whole journey.

  1. $ 14\cfrac{1}{3} $ km/hr
  2. $ 52\cfrac{1}{3} $ km/hr
  3. $ 75\cfrac{1}{3} $ km/hr
  4. $ 63\cfrac{1}{3} $ km/hr
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Total distance = 570 km. Part 1: 224 km at 56 km/hr = 4 hours. Part 2: 210 km at 70 km/hr = 3 hours. Remaining distance = 570 - 224 - 210 = 136 km. Time for remaining = 2 hours. Total time = 4 + 3 + 2 = 9 hours. Average speed = 570 / 9 = 63.33 km/hr = 63 1/3 km/hr.

AI explanation

To find the total journey time, calculate the time taken for each segment by dividing the distance by its respective speed, yielding 224 divided by 56 to equal 4 hours, and 210 divided by 70 to equal 3 hours. Adding the 2 hours taken for the final segment gives a total time of 9 hours. The average speed is the total distance of 570 km divided by this total time of 9 hours. This calculation results in an average speed of 63 1/3 km/hr for the whole journey.

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