Rahul ranked ninth from the top and thirty-eighth from the bottom in a class. How many students are there in the class?

Manoj and Sachin are ranked seventh and eleventh respectively from the top in a class of $31$ students. What will be their respective ranks from the bottom in the class?

Some boys are sitting in a row. $P$ is sitting fourteenth from the left and $Q$ is seventh from the right. If there are four boys between $P$ and $Q,$ how many boys are there in the row?

How many $8$'s are there in the following number series which are exactly divisible by their immediately preceding and also divisible by their immediately succeeding numbers?
$8, 2, 4, 5, 1, 7, 2, 8, 4, 8, 4, 2, 2, 8, 2, 6, 9, 8, 4, 5, 4, 8, 3, 2, 8, 4, 3, 1, 8, 3$

In the following list of numerals,how many $2$'s are followed by $1$'s but not preceded by $4$?

The letters $L, M, N, O, P, Q, R, S$ and $T$ in their order are substituted by nine integers $1$ to $9$ but not necessarily in that order. $4$ is assigned to $P$. The difference between $P$ and $T$ is $5$. The difference between $N$ and $T$ is $3$. What is the integer assigned to $N$?