A soil sample was taken from the clay layer shown in the figure below. The sample was tested in the laboratory using the $1-$dimensional consolidation laboratory test $($oedometer$).$ The sample height was $20mm$ and the time for $90\%$ consolidation was $(50-2x)$ minutes.

$($i$)$ Compute $C_v$ in $\frac{m^2}{?}$ year

$($ii$)$ What will be the time for $90\%$ consolidation in the field?

$($iii$)$ If the total consolidation settlement is $50mm,$ how much settlement will occur in the field in $2$ years?

$($iv$)$ If there is sand instead of the bedrock and there is a thin sand layer $(40cm$ thick$)$ at the middle of the clay layer. What effect this thin sand layer will have on the time rate of settlement in $($ii$)$ above?

Bedrock