Multiple choice

A boy travels a distance of 8 km. at the rate of 4km./hr.,6 km. at the rate of 3 km./hr. and 4 km.at the rate of 2 km./hr. What is the average speed for the entire journey?

  1. 2.5 km./hr.

  2. 3 km./hr.

  3. 4.2 km./hr.

  4. 5 km./hr.

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Average speed = total distance / total time. Time = 8/4 + 6/3 + 4/2 = 2 + 2 + 2 = 6 hours. Total distance = 18 km. Average speed = 18/6 = 3 km/hr. NOT the average of speeds.