$4$ coins are tossed once. Find the probability of getting at least $1$ tail.

Two cards are drawn one by one at random from a pack of $52$ cards. The probability that both of them are kings is:

$A$ bag contains $5$ white,$7$ black,and $4$ red balls. Three balls are drawn from the bag at random. The probability that all the three balls are white is:

An urn contains $25$ balls numbered $1$ to $25$. Suppose an odd number is considered a 'success'. $2$ balls are drawn from the urn with replacement. Find the probability of getting at least one success.

What is the probability that a leap year selected at random will contain $53$ Sundays?

$A$ locker can be opened by dialing a fixed three-digit code (between $000$ and $999$). $A$ stranger who does not know the code tries to open the locker by dialing three digits at random. The probability that the stranger succeeds at the $k^{th}$ trial is