Question

Billy likes to go cycling. His bike has wheels of the diameter 70 cm. He has a counter on his bike which counts the number of revolutions of the wheels make. One day the counter shows 190 revolutions. How far has Billy cycled? Give your answer to the nearest meter.

Answer 1

401 meters

Explanation:

To change the units without changing the value, we use the Multiplicative Identity (that is, 1).

The formula for the circumference of a circle is: C=Πd

The problem gives d=85 cm, so C=85Π cm. So, (1 revolution)=(85Π cm)

or 1= (85Π cm) / (1 revolution)

Billy traveled:

150 revolutions

(150 revolutions)*1

(150 revolutions) * ( (85Π cm) / (1 revolution) ) [note: revolutions cancel, leaving only cm]

(150)*(85Π) cm

40055.27 cm * ( (1 meter)/(100 cm) )

401 meters (rounded to nearest meter)

(this isnt my work credits to David W.