Four coins are tossed. The probability that at least one head turns up is

$A$ and $B$ are two independent events such that $P(A) = 1/2$ and $P(B) = 1/3$. Then $P$ (neither $A$ nor $B$) is equal to

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

$A$ positive integer is selected at random and is divided by $9$. What is the probability that the remainder is equal to $1$ (in $/9$)?

One card is drawn from each of two ordinary packs of $52$ cards. The probability that at least one of them is an ace of heart,is

$A$ determinant is chosen at random from the set of all determinants of order $2$ with elements $0$ or $1$ only. The probability that the determinant chosen is non-zero is