Question 122205
swimming pool 20 feet wide 
           and 40 feet long 

So Circumference=2(wide+long)
=2(20+40)
=2(60)
=120

So minimum 120 tiles of 1 ft length needed
Plus 4 tiles at the corner
So Totally 120+4=124 tiles
okay

Verify: Take a graph sheet
scale 1ft=1mm
Draw the outline and understand

Answer = 124 tiles