WBCS Mains 2018 Official Paper-VI

How many such $5\text{s}$ are there in the following number sequence, each of which is immediately preceded by $3$ or $4$ but not immediately followed by $8$ or $9$?
$$\text{3 5 9 5 4 5 5 3 5 8 4 5 6 7 3 5 7 5 5 4 5 2 3 5 1 0}$$

If it is possible to form a number with the second, the fifth, and the eighth digits of the number $31549786$, which is a perfect square of a two-digit even number, which of the following will be the second digit of that even number?

Rohan ranks seventh from the top and twenty-sixth from the bottom in a class. How many students are there in the class?

If $30^{\text{th}}\text{ January 2003}$ was a Thursday, what was the day of the week on $2^{\text{nd}}\text{ March 2003}$?

If $20-10=200$, $8÷4=12$, and $6\times 2=4$, find the value of the expression:
$$100\times 10-1000+1000÷100-10$$