In the following experiment,specify the appropriate sample space: $A$ person is noting down the number of accidents along a busy highway during a year.

$A$ speaks truth in $20 \%$ of the cases and $B$ in $80 \%$ of the cases. Find the probability that their statements about an incident do not match.

Three coins are tossed once. Find the probability of getting $3$ tails.

Let $S$ be the sample space of the random experiment of throwing simultaneously two unbiased dice with six faces (numbered $1$ to $6$) and let $E_k = \{(a, b) \in S : ab = k\}$ for $k \geq 1$. If $p_k = P(E_k)$ for $k \geq 1$,then which of the following is correct?

$A$ problem in statistics is given to three students $A, B$ and $C$. Their probabilities of solving the problem are $\frac{1}{2}, \frac{1}{3}$ and $\frac{1}{4}$ respectively. If all of them try independently,then the probability that the problem is solved is

The probabilities of winning the race by two athletes $A$ and $B$ are $\frac{1}{5}$ and $\frac{1}{4}$ respectively. The probability that neither of them wins the race is: