The chances to fail in Physics are $20\%$ and the chances to fail in Mathematics are $10\%$. What are the chances to fail in at least one subject? ............ $\%$

Consider the experiment in which a coin is tossed repeatedly until a head comes up. Describe the sample space.

Six faces of an unbiased die are numbered with $2, 3, 5, 7, 11$ and $13$. If two such dice are thrown,then the probability that the sum on the uppermost faces of the dice is an odd number is

If a number $x$ is drawn randomly from the set of numbers $\{1, 2, 3, \ldots, 50\}$,then the probability that the number $x$ satisfies the inequation $x + \frac{10}{x} \leq 11$ is

$A, B, C$ are aiming to shoot a balloon. $A$ will succeed $4$ times out of $6$ attempts. The chance of $B$ to shoot the balloon is $3$ out of $5$ and that of $C$ is $2$ out of $3$. If the three aim to shoot the balloon simultaneously,then the probability that at least two of them hit the balloon is

If two dice are thrown simultaneously,what is the probability of getting $1$ on the first die?