The probability that a student will pass the final examination in both English and Hindi is $0.5$ and the probability of passing neither is $0.1$. If the probability of passing the English examination is $0.75$, what is the probability of passing the Hindi examination?
Let $A$ and $B$ be the events of passing English and Hindi examination respectively.
Accordingly, $P ( A $ and $B)=0.5$, $P ($ not $A$ and $B )=0.1,$
i.e., $P \left( A^{\prime} \cap B ^{\prime}\right)=0.1$
$P ( A )=0.75$
Now, $P ( A \cap B ) ^{\prime}= P \left( A ^{\prime} \cap B ^{\prime}\right)$ [De Morgan's law]
$\therefore P(A \cap B)^{\prime}=P\left(A^{\prime} \cap B^{\prime}\right)=0.1$
$P ( A \cup B )=1- P ( A \cup B )^{\prime} =1-0.1=0.9$
We know that $P ( A$ or $ B )= P ( A )+ P ( B )- P ( A$ and $ B )$
$\therefore $ $0.9=0.75+ P ( B )-0.5$
$\Rightarrow P ( B )=0.9-0.75+0.5$
$\Rightarrow P(B)=0.65$
Thus, the probability of passing the Hindi examination is $0.65$.
From the employees of a company, $5$ persons are selected to represent them in the managing committee of the company. Particulars of five persons are as follows :
S.No. | Name | Sex | Age in years |
$1.$ | Harish | $M$ | $30$ |
$2.$ | Rohan | $M$ | $33$ |
$3.$ | Sheetal | $F$ | $46$ |
$4.$ | Alis | $F$ | $28$ |
$5.$ | Salim | $M$ | $41$ |
A person is selected at random from this group to act as a spokesperson. What is the probability that the spokesperson will be either male or over $35$ years?
The chance of an event happening is the square of the chance of a second event but the odds against the first are the cube of the odds against the second. The chances of the events are
The probabilities of occurrence of two events are respectively $0.21$ and $0.49$. The probability that both occurs simultaneously is $0.16$. Then the probability that none of the two occurs is
If $P\,(A) = 0.4,\,\,P\,(B) = x,\,\,P\,(A \cup B) = 0.7$ and the events $A$ and $B$ are mutually exclusive, then $x = $
A card is drawn at random from a pack of cards. The probability of this card being a red or a queen is