Question

The spoke of a wheel reaches from the center of the wheel to its rim. If the circumference of the rim of the wheel is 42 inches, how long is each spoke? Round your answer to the nearest hundredth.
A. 6.69 inches
B. 6.25 inches
C. 7 inches
D. 13.38 inches

Answer 1

The circumference of the wheel can be expressed by:

$circumference = 2 \pi r$
Where r = the radius of the wheel.

Since the spoke reaches from the center of the wheel to its rim then r = length of the spoke

By rearranging the circumference equation we get:

$r = \frac{circumference}{2 \pi }$

If circumference = 42 inches then:

$r = \frac{42}{2 \pi }$

r = 6.68
Which is closest to B

Your book may have a typo in it as the answer to 4 decimal places is 6.6845 which rounds down to 6.68, not up to 6.69.