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

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

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

$(I)$ Kamal is available at home from $12$ noon to $4 \,p.m.$ on Tuesday,Thursday,and Sunday.
$(II)$ His younger brother Navin is available at home on Monday,Thursday,Friday,and Sunday between $10 \,a.m.$ to $2 \,p.m.$
$(III)$ The eldest brother Rajiv is available between $9 \,a.m.$ to $12$ noon on Monday,Wednesday,and Thursday and $2 \,p.m.$ to $4 \,p.m.$ on Friday,Saturday,and Sunday.
For how many days is only one brother available at a particular time in a week?

In a class of $40$ students,Samir's rank from the top is $12^{th}$. Alok is $8$ ranks below Samir. What is Alok's rank from the bottom?

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