The diameter of the semicircle is 16 feet.
He calculates that he needs to buy abut 25.12 feet of fencing.
To find amount of fencing we find the circumference of semicircle
Circumference of semicircle =
Where d is the diameter of the circle
d= 16 given and value of pi is 3.14
Circumference of semicircle =
=25.12 + 16 = 41.12 feet
Scott's calculation was wrong because he forgot to add the diameter d
Circumference of circle is half way of circle plus the diameter of circle.
Correct amount of fencing = 41.12 feet