Question

Stacy needs to find the circumference of a circle with a diameter of 15 inches. She needs a pretty accurate answer, so she uses a calculator. Which answer is reasonable?

45.143672 in
47.123889 in
49.068423 in
50.714805 in

Answer 1

47.123889 in

Explanation:

To find circumference is always diameter times 3.14 or radiuspi2.

Answer 2

47.123889 in

Explanation:

The given answer choice (above) uses a value of π that is 3.1415926, which is accurate as far as it goes, but is improperly rounded in the last digit. (The next digits are ...535897932384626..., so it should be rounded to 7 in the last shown decimal place.

The properly rounded value of circumference would be 47.123890 in. The best answer choice is ...

47.123889 in