Question

The formula for the circumference, C, of a circle with given radius, r, is C = 2nr.

What is the circumference of a circle with a radius of 3 1-2 meters?
(Use 21
22
as an estimate for n.)
A. 7 meters
B. 11 meters
C. 22 meters
D. 44 meters

Answer 1

C. 22

Explanation:

C = circumference

n (pi) = 22/7

r = 3 1 /2

Plug in the numbers for each variable.

C = 2x (22/7) x (3 1/2)

Change the mixed number inIto an improper fraction by multiplying 3 x 2 and adding the 1 which gives us 7 over 2 because 2 is our denominator so, 3 1/2 = 7/2. It also helps to have 1 as the denominator for 2.

C = (2/1) x (22/7) x (7/2)

Lastly, just multiply the numerators across which give us 308 then multiply the denominators across which gives us 14, so then we divide 308 by 14 and get 22.