Three unbiased coins are tossed once. What is the probability of getting at most two heads?

If $A$ and $B$ are mutually exclusive events,then the value of $P(A \text{ or } B)$ is

In a single throw of two dice,the probability of obtaining an odd number as the sum is

$A$ bag contains $13$ red,$14$ green,and $15$ black balls. The probability of getting exactly $2$ black balls when pulling out $4$ balls is ${P_1}$. Now,the number of balls of each color is doubled,and $8$ balls are pulled out. The probability of getting exactly $4$ black balls is ${P_2}$. Then:

$2$ dice are thrown. Find the probability of getting an odd number as the sum.

In a simultaneous throw of $2$ dice,find $P(A \text{ or } B)$ if $A$ denotes the event 'a total of $11$' and $B$ denotes the event 'an odd number on each die'.