Problem 11 · 2015 Math Kangaroo
Medium
Ratios, Rates & Proportions
distance-speed-timeunit-rate
A cyclist covers a distance of 5 m in one second. The wheels of his bike each have a circumference of 125 cm. How many complete turns does each wheel make in 5 seconds?
Show answer
Answer: D — 20
Show hints
Hint 1 of 2
First find how far the bike travels in 5 seconds, then how far one wheel turn moves it.
Still stuck? Show hint 2 →
Hint 2 of 2
One full turn moves the bike one circumference; divide the distance by the circumference (watch the units).
Show solution
Approach: distance over circumference
- In 5 seconds the bike covers 5 * 5 = 25 m = 2500 cm.
- Each full wheel turn moves it forward one circumference, 125 cm.
- Number of turns = 2500 / 125 = 20.
- So each wheel makes 20 (D) complete turns.
Mark:
· log in to save