A raft foundation of $30\:m \times 25\:m$ is proposed to be constructed at a depth of $8\:m$ in a sand layer. A $25\:m$ thick saturated clay layer exists $2 m$ below the base of the raft foundation. Below the clay layer, a dense sand layer exists at the site. A $25\:mm$ thick undisturbed sample was collected from the mid-depth of the clay layer and tested in a laboratory oedometer under double drainage condition. It was found that the soil sample had undergone $50 \%$ consolidation settlement in $10$ minutes.
The time (in days) required for $25\%$ consolidation settlement of the raft foundation will be _______________ (round off to the nearest integer)