Diameter of a semi circular garden = 18 feet
Radius of the garden :
Thus, the radius of the semi circular fence = 9 feet
We know that :
Which means, the circumference of Mary's semi circular garden :
(pi value = 3.14)
Thus, the circumference of fence needed for the semi circular garden = 28.26 feet
28.26 can be rounded off to 28.30 and 28.30 is the same as 28.3
Thus, Mary's reasoning is correct.
Therefore, Mary's reasoning is correct which means she needs 28.3 feet of fence to surround her garden.
