Using a safety factor of 2.00 and neglecting the pile dead weight, find the length of a 1' diameter circular concrete pile required to take a design load of 50 kips in a soil composed of two layers. The top, 20 foot layer is a medium clay with an adhesion factor of 0.630 kips per square foot and a bearing capacity of 6.5 kips per square foot. The second layer of unknow depth is a stiff clay with an adhesion factor of 1.12 kips per square foot and a bearing capacity of 18.0 kips per square foot. Find the total length(depth) of the pile.