Multiple choice

One-third of a certain journey was covered at the speed of 20 km./hr., one-fourth at 30 km./hr. and the rest at the speed of 50 km./hr. The average speed per hour for the whole journey is - एक यात्रा का एक तिहाई 20 किमी./घं. की चाल से, एक चौथाई 30 किमी./घं. की चाल से और शेष 50 किमी./घं. की चाल से तय की जाती है। पूरी यात्रा में औसत चाल प्रति घंटा क्या है?

  1. 33.33

  2. 30

  3. 28

  4. 25
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

For average speed, we need total distance divided by total time, not the average of speeds. Let total distance be 12 units (LCM of 3, 4, and remaining 5). Time taken: 4 units at 20 km/h = 0.2h, 3 units at 30 km/h = 0.1h, 5 units at 50 km/h = 0.1h. Total time = 0.4h, so average speed = 12/0.4 = 30 km/h. Option A (33.33) incorrectly averages the speeds.

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