Two balanced dice are rolled. Find the probability that the sum of numbers on two dice is odd.

Find the probability of getting number $2$ on a die when a fair die is thrown.

$A$ class consists of $35$ boys and $25$ girls. One student is selected at random to be the class monitor. Find the probability that the selected student is a girl. (in $/12$)

There are $1000$ sealed envelopes in a box,$10$ of them contain a cash prize of $Rs. 100$ each,$100$ of them contain a cash prize of $Rs. 50$ each,$200$ of them contain a cash prize of $Rs. 10$ each,and the rest do not contain any cash prize. If they are well shuffled and an envelope is picked out,what is the probability that it contains no cash prize?

$A$ student attends a $50$ mark test. No negative marks are given in the test. Find the probability that he scores $30$ or $35$ marks.

Total number of outcomes in the experiment of tossing an unbiased coin twice is ..........