$A$ coin is tossed $4$ times. The probability that at least one head turns up is

Consider the circuit shown in the image. If the probability that each switch is closed is $p$,then find the probability of current flowing through $AB$.

$A$ bag contains $13$ white and $7$ black balls. $2$ balls are drawn at random. What is the probability that they are of the same colour?

$A$ coin is tossed $3$ times by $2$ persons. What is the probability that both get an equal number of heads?

$A$ bag contains $6$ red,$4$ white and $8$ blue balls. If three balls are drawn at random,then the probability that $2$ are white and $1$ is red,is

The probability that a man will be alive $25$ years hence is $0.3$ and the probability that his wife will be alive $25$ years hence is $0.4$. Find the probability that $25$ years hence, at least $1$ of them will be alive.