Diameter of a circle

Question

Ali measured the Circumference of a tree trunk. Its Circumference is 91 feet. What is its approximate diameter, rounded to the nearest foot?

Answer 1

circumference=(pi)*diameter

there are many approximations for pi; 3.14, 3.14159, 3.1416, and 22/7

C=(pi)*d

91=3.14*d

91/3.14=d

d=28.98

d=29 feet

91=(3.14159)*d

91/3.14159=d

d=28.96

d=29 feet

91=(22/7)*d

91*(7/22)=d

637/22=d

d=28 21/22

d=29 feet