Question

The minute hand of the clock is 5 inches long. How far does the tip of the minute hand move in 4 full rotations? Calculate your answer using the pi button on your calculator and round to the nearest tenth of an inch.

Answer 1

Assuming the clock to be round in shape, we can treat the minute hand length as the radius of the circle.

We want to know the length, in inches, of 4 full rotations.

1 full rotation length is the circumference of the circle with radius 5 (minute hand is radius and has length 5 inches). We use the formula of the circumference of a circle to get length in 1 rotation:

$C=2\pi r\\C=2\pi (5)\\C=10\pi$

So for 4 full rotations, the length covered is $4*10\pi=40\pi$ inches.

Rounding to nearest tenth of an inch, we have:

$40\pi=125.7$ inches

ANSWER: $40\pi$ or 125.7 inches

Answer 2

4 full rotations = 4 * 2πr = 40π is 125.7 inches