A bag contains $9$ discs of which $4$ are red, $3$ are blue and $2$ are yellow. The discs are similar in shape and size. A disc is drawn at random from the bag. Calculate the probability that it will be either red or blue.
There are $9$ discs in all so the total number of possible outcomes is $9 .$
Let the events $A, \,B, \,C$ be defined as
$A:$ 'the disc drawn is red'
$B:$ 'the disc drawn is yellow'
$C:$ 'the disc drawn is blue'.
The event 'either red or blue' may be described by the set $'A$ or $C'$
since, $A$ and $C$ are mutually exclusive events, we have
$P ( A \text { or } C )= P ( A \cup C )$ $= P ( A )+ P ( C )=\frac{4}{9}+\frac{1}{3}=\frac{7}{9}$
An event has odds in favour $4 : 5$, then the probability that event occurs, is
If $P(A) = P(B) = x$ and $P(A \cap B) = P(A' \cap B') = \frac{1}{3}$, then $x = $
One card is drawn at random from a well shuffled deck of $52$ cards. In which of the following cases are the events $\mathrm{E}$ and $\mathrm{F}$ independent ?
$E:$ ' the card drawn is a king and queen '
$F:$ ' the card drawn is a queen or jack '
The odds against a certain event is $5 : 2$ and the odds in favour of another event is $6 : 5$. If both the events are independent, then the probability that at least one of the events will happen is
$A$ and $B$ are two events such that $P(A)=0.54$, $P(B)=0.69$ and $P(A \cap B)=0.35.$ Find $P \left( A \cap B ^{\prime}\right)$ .