We need the circumference and area of the circle equations:
c = 2*pi*r
a = pi*r^2
lets find the radius from the first equation:
r = c/2*pi
r = 157/(2*3.14)
r = 24.99 ft
now lets calculate the area:
a = pi*r^2
a = 3.14*(24.99)^2
a = 1960.93 ft^2
Now we need to divide the total area by the rate at which Chris paints, and that gives us the time needed:
time = 1960.93/400
time = 4.9 hours
that would be 5 hours rounded to the nearest hour
