Question

The wheels of bicycles A and B have radii 30 cm and 40 cm, respectively. While traveling a certain distance, each wheel of A required 5000 more revolutions than each wheel of B. If bicycle B traveled this distance in 45 minutes, then its speed, in km per hour, was

• A. 18π
• B. 12π
• C. 16π
• D. 14π

Answer 1

The Correct Option is B

Distance for bicycle A in one revolution = 60π cm and for bicycle B = 80π cm.
Let B make 'n' revolutions to cover the distance, then A would make (n + 5000) revolutions to cover the same distance.
Equation: n × 80π = (n + 5000) × 60π Solving for n gives n = 15000.
Distance traveled by B = n × 80π cm = 12 km.
Time taken by B = 45 min = 3/4 hrs.
Therefore, the speed of B = 16π km/h.