we know that
To find out the probability divide the area of the hole by the total area
the area of a circle is equal to
A=pir^2
total area
D=75 ft
r=D/2
r=75/2=37.5 ft
A=pi(37.5^2)
A=1,406.25 pi ft^2
Find the area of the hole
D=15 ft
r=D/2
r=15/2=7.5 ft
pi(7.5^2)
A=56.25pi ft^2
Find the probability
P=56.25pi/1,406.25 pi
P=0.04
or
P=4%