To find out how much the contractor will spend on tiles, you will need to find the area of the circular space. 
 Use the formula for finding area of a circle. 
A = pi x r^2
  3.14 x 60^2
A=   11,304 in.². 
 Multiply this by $0.04 per square inch. 
11304 x 0.04 = $452.16
  The cost is $452.16.