RERA is associated with regulation of which of the

Select the number from among the given options that can replace the question mark (?) in the following series.

64, 60, 52, 40, ?, 4

12, 24, 72, 288, 1440, ?

14      15        32       99       400       ?

3 2 2 3 8 ?

12, 23, 68, 271, 1354, ?

Compute Σ (1 / (k(k+1))) from k = 1 to 10.

25 30 300 315 6300 ?

If          3     2      1       x           4        12.5,

then,  (x²-1) (x²+1) = ?

15         12        ?          9         21         6

21      84       168        172      ?      348