Design a $7\mathrm{.}5$ m by $6\mathrm{.}5$ m slab as one$-$way hollow block slab in the short direction. The slab is supported on beams of width $300$ mm $.$ It is subjected to a dead load of $3k\frac{N}{m^2}$ and an imposed load of $4k\frac{N}{m^2}.$ Take characteristic material strengths as $f_{cu}=25\frac{N}{m}{m}^2$ and $f_y=460\frac{N}{m}{m}^2.$ Use the following design data.

$310\mathrm{.}45$

$\backslash$table$[[$Whith of ribs,$150$ mm$],[$Topping$,75$ mm$],[$Blocks$,225$ mm by $225$ mm by $375$ mmt$],[$Weight of one block,$20$ kg$]]$