Which number will come next in the following series?
$2, 1, 2, 1, 3, 2, 1, 3, 4, 2, 1, 3, 4, 5, 2, 1, 3, 4, 5, 6, 2, 1, 3, 4, 5, ?$

Choose the correct alternative to complete the series: $a . c . a b b . . a . b e . b e . . a b$

Choose the correct alternative for the missing term in the series: $AZ, BY, CX, ?$

To answer these questions, study the following arrangement of digits, letters and symbols carefully.

$6, N,P ,=,@, 7,1 ,\&, R, T, 3, L, ,B, \star, E ,4,\# ,8, G,H ,\$, 5, K,M ,?, 2, D,C$

If all the digits in the arrangement are deleted, which of the following will be midway between the $3^{rd}$ and the $15^{th}$ elements from the left end?

How many such $4$s are there in the following number series,each of which is immediately followed by $5$ but not immediately preceded by $3$?
$5, 4, 4, 3, 3, 4, 5, 4, 5, 5, 3, 4, 4, 3, 4, 5, 4, 3, 3, 5, 4, 5, 4, 3, 5, 4, 4, 3, 5, 4$

Choose the correct alternative to fill in the blanks in the series: $....bbca....bcca......ac.....a...cb$