A site is underlain by a 4m thick layer of sand. Below the sand layer lies a clay layer with void ratio = 0.96, compression index = 0.23, and recompression index = 0.04. Below the clay layer lies rock. The water table is located 3m below the ground surface. On January 11th, a 3m high fill with γ = 17 kN/m³ is placed on the ground surface. Ninety days later, the site surveyors find that the ground surface has subsided 13 cm, and the geotechnical engineering team attributes this subsidence to consolidation of the clay layer. Calculate the coefficient of consolidation of the clay layer. Show your work and circle your answer.