A site is underlain by a $4m$ thick layer of sand. Below the sand layer fies an with void ratio $=0\mathrm{.}96,$ compression index $=0\mathrm{.}23,$ and recompression index $=0\mathrm{.}04.$ Below the clay layer lies rock. The water fable is located $3m$ below the ground surface On January $11$t$,$ a $3m$ high fill with $y=17k\frac{N}{m^3}$ is placed on the ground surface. Ninety days later, the site surveyors find that the ground surface has subsided $13cm.$ and the geotechnica engineering team attributes this subsidence to consolidation of the clay layer. Calculate the coefficient of consolidation o the clay layer. Show your work and circle your answer.