Posted by **jake** on Sunday, February 6, 2011 at 10:45am.

if the diameter of a bike wheel is 20cm, what's the minimum number of revolutions needed to cover 1km?

- maths -
**dave**, Sunday, February 6, 2011 at 10:56am
1km = 1000 m

100cm = 1 m

convert to meters and divide

- maths -
**helper**, Sunday, February 6, 2011 at 11:19am
Diameter d = 20 cm

Circumference C = pi * d

C = 3.14 * 20 = 62.8 cm in one revolution

62.8 cm

100 cm = 1m

62.8/100 = 0.628 m

0.628 m in one revolution

1 km = 1000 m

1000/0.628 = 1592.36 revolutions

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