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

Madhu is $18^{th}$ from the left end and Sandhu is $11^{th}$ from the right end of a row of $40$ children. How many children are there between Madhu and Sandhu in the row?

Count each $1$ in the following sequence of numbers that is immediately followed by $2$,if $2$ is not immediately followed by $3$. How many such $1$'s are there?
$1, 2, 1, 3, 4, 5, 1, 2, 3, 5, 2, 1, 2, 6, 1, 4, 5, 1, 1, 2, 4, 1, 2, 3, 2, 1, 7, 5, 2, 1, 2, 5$

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 $21$ 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 $^{th}$)?

Satish remembers that his brother's birthday is after $15^{th}$ but before $18^{th}$ of February,whereas his sister Kajal remembers that her brother's birthday is after $16^{th}$ but before $19^{th}$ of February. On which day in February is Satish's brother's birthday (in $^{th}$)?