A runners average speed reduces by 25% every hour. If he runs 16 km in the first hour

A runner's average speed reduces by 25% every hour. If he runs 16 km in the first hour and he runs for 3 hours, then what is his overall average speed?

1.  12 km/hr
2.  12.33 km/hr
3.  10.33 km/hr
4.  13 km/hr

• Answer: The correct option is B
• Explanation:

  First hour

  The runner covers 16 km in the first hour.

  Speed = 16 km/hr

  Second hour

  His speed reduces by 25%.

  Distance in the second hour = 12 km

  Third hour

  His speed again reduces by 25%.

  Distance in the third hour = 9 km

  Total distance = 16 km + 12 km + 9 km = 37 km

  Total Time = 3 hours

  Average speed = Total Distance / Total Time

  = 37/3 = 12.33 km/hr