In FCC , 50% tetrahedral void is filled. Find the effective number of atoms in cell if made using the same atoms

Diamond exists in FCC unit cell with 50% tetrahedral sites also occupied. The effective number of carbon atoms in a unit cell of diamond is

The number of tetrahedral voids are formed if the number of atoms in a crystal is N/2

In sc, bcc and fcc the ratio of number of atoms per unit cell is given by

In any ionic crystal A has formed cubical close packing and B atoms are present at every tetrahedral voids. If any sample of crystal contain 'N' number of B atoms then number of A atoms in that sample is

Number of tetrahedral voids occupied in a unit cell of diamond is