$1.12.91$ is the first Sunday. Which is the fourth Tuesday of December $91$ (in $.91$)?

Among $M, N, P, R$ and $T$,each one has secured different marks in an examination. $R$ secured more marks than $M$ and $T$. $N$ secured less marks than $P$. Who among them secured the third highest marks?

How many $7$'s are there in the following series which are not immediately followed by $3$ but immediately preceded by $8$?
$8, 9, 8, 7, 6, 2, 2, 6, 3, 2, 6, 9, 7, 3, 2, 8, 7, 2, 7, 7, 8, 7, 3, 7, 7, 9, 4$

In a row of $21$ girls, when Monika was shifted by four places towards the right, she became $12^{th}$ from the left end. What was her earlier position from the right end of the row (in $^{th}$)?

In a row of girls,Rita and Monika occupy the ninth place from the right end and tenth place from the left end,respectively. If they interchange their places,Rita and Monika occupy seventeenth place from the right and eighteenth place from the left,respectively. How many girls are there in the row?

In the series,$6, 4, 1, 2, 2, 8, 7, 4, 2, 1, 5, 3, 8, 6, 2, 1, 7, 1, 4, 1, 3, 2, 8, 6$,how many pairs of successive numbers have a difference of $2$ each?