Multiple choice

A biker increases his speed by 10% after travelling for 1 hour every time. He covers 198.6 km in 3 hour. Average speed in last 2 hours (in km/hr) is?

  1. 58.4

  2. 66.6

  3. 69.3

  4. 63.8
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let initial speed = v km/h. Hour 1: distance = v. Hour 2: speed = 1.1v, distance = 1.1v. Hour 3: speed = 1.21v, distance = 1.21v. Total: v + 1.1v + 1.21v = 3.31v = 198.6, so v = 60. Hour 2 speed = 66, Hour 3 speed = 72.6. Avg last 2 hrs = (66 + 72.6)/2 = 69.3 km/h. The progressive 10% increases create this average.

Keep practicing — related questions