If $1^{st}$ October is Sunday,then $1^{st}$ November will be

How many numbers from $11$ to $50$ are there which are exactly divisible by $7$ but not by $3$?

In the following series of numbers,how many times have the figures $9, 1,$ and $8$ appeared together,with $1$ being in the middle and $9$ and $8$ being on either side of $1$ (i.e.,the sequence $9, 1, 8$ or $8, 1, 9$)?
$2, 1, 9, 8, 1, 9, 8, 3, 7, 1, 9, 7, 8, 1, 2, 9, 1, 9, 8, 1, 8, 2, 1, 2$

In a queue,Amrita is $10^{th}$ from the front while Mukul is $25^{th}$ from behind and Mamta is just in the middle of the two. If there are $50$ persons in the queue,what position does Mamta occupy from the front (in $^{th}$)?

In a row of $21$ girls, when Anita 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 the following number sequence,how many such even numbers are there which are exactly divisible by its immediate preceding number but not exactly divisible by its immediate following number?
$3, 8, 4, 1, 5, 7, 2, 8, 3, 4, 8, 9, 3, 9, 4, 2, 1, 5, 8, 2$