Question

The diameter of your bicycle wheel is 25 inches. How far will you move in two turns of your wheel? Use 3.14 for π.
A) about 39 inches
B) about 78 inches
C) about 157 inches
D) about 314 inches

Answer 1

$circumference \: = 2\pi \: r$
diameter = 25 inches
radius = 25/2
= 12.5 inches

= 2(3.14)(12.5)
= 78.5 inches ( for a turn )

Two turns = 78.5 inches X 2
= 157 inches

C.

Answer 2

Answer: D) About 314 inches

Step-by-step explanation:

Since, the radius of the wheel = 25 inches

Also, the angle in one turns of the wheel $= 2\pi$

⇒ The angle in 2 turn of the wheel $= 4\pi$

Hence, the distance it will cover in two turns

$= 4\pi\times 25$       ( Arc length = central angle × radius)

$= 4\times 3.14\times 25$

$=314.159265\approx 314\text{ inches}$

⇒ Fourth option is correct.