Questions

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28 questions · timed · auto-graded

Question 12 Marks
Two cards are selected from a pack of $52$ cards one by one without replacement. Find the probability of getting an ace and a king in that order.
Answer
$\frac{4}{663}$
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Question 22 Marks
Find the probability that at least one die shows digit $4 ,$ when two dice are thrown simultaneously.
Answer
$\frac{11}{36}$
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Question 32 Marks
There are $3$ yellow and $7$ white flowers in a basket. Two flowers are selected one by one without replacement from it. Find the probability that the first flower is yellow and the second flower is white.
Answer
$\frac{7}{30}$
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Question 42 Marks
$7$ eitizens of country $A$ and $5$ citizens of country $B$ are traveling in an international flight of a company. After the routine security check, a higher level officer randomly selects $2$ citizens without replacement from the citizens of these two countries for additional security. Find the probability that both the selected citizens are from different countries.
Answer
$\frac{35}{66}$
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Question 52 Marks
If $P(A)=\frac{2}{3}, P(B)=\frac{2}{5}$ and $P(A / B)=\frac{1}{2}$, find $P(B / A)$.
Answer
$\frac{3}{10}$
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Question 62 Marks
The result of a school reveals that $20 \%, 15 \%$ and $30 \%$ students have failed in a school exam of standard $12$ in the subjects of Statistics, Economics and at least one of these subjects respectively. A student is selected at random from this school. If it is known that the student has failed in Economics, find probability that he has failed in Statistics, too.
Answer
$\frac{1}{3}$
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Question 72 Marks
For a couple, the probability that the husband will be alive for next ten year is $0.7$ and that of his wife will be alive is $0.8$. The probability that both will be alive is $0.6$.
At the end of ten years. $(1)$ If the husband is alive, find the probability that the wife will be alive.
$(2)$ If the wife is alive, find the probability that the husband will be alive.
Answer
$(1)\ \frac{6}{7}$ $(2)\ \frac{3}{4}$
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Question 82 Marks
The probability of occurring at least one event out of two events $A$ and $B$ is $\frac{2}{3}$ and the probability of occuring $B$ but not $A$ is $\frac{1}{5}$. Find the probability of event $A$.
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Question 92 Marks
Using the following information, find $P(A \cup B \cup C)$ for three events $A, B$ and $C$ of the sample space of a random experiment$\begin{aligned} &P(A)=0.63, P(B)=0.44, P(C)=0.27, P(A \cap B)=0.23, P(A \cap C)=0.16, P(B \cap C)=0.21, \\ &P(A \cap B \cap C)=0.04 \end{aligned} $
Answer
$\frac{7}{5}$
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Question 102 Marks
A book of Statistics subject of $12 th$ standard is divided into two parts. There are $4$ chapters in part $1$ and $5$ chapters in part $2.$ A student selects any two chapters for revision in the end of January month.
$(1)$ Find the probability that the chapters selected by the student are from the same part.
$(2)$ Find the probability that the chapters selected by the student are from different parts
Answer
$0.78$
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Question 112 Marks
A teacher prepares schedule for the examination of seven subjects. Find the probability that the paper of Gujarati subject is scheduled immediately after the paper of English subject.
Answer
$(1)\ \frac{4}{9}$
$(2)\ \frac{5}{15}$
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Question 122 Marks
For two events $A$ and $B$ of sample space of a random experiment, $P(A)=0.7, P(B)=0.4$ and $P(A \cap B)=0.1$. Find $P(A-B)$ and $P\left(A^{\prime} \cap B^{\prime}\right)$.
Answer
$\frac{1}{7}$
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Question 132 Marks
Two cards are selected at random from the pack of well-shuffled cards.
$(1)$ Find the probability of having both the cards of same suit.
$(2)$ Find the probability of having one face card
Answer
$P(A-B)=0.6, P\left(A^{\prime} \cap B^{\prime}\right)=0$
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Question 142 Marks
The sample space of a random experiment for selecting one number is $U=\{1,2,3, \ldots \ldots, 80\}$. All outcomes of this sample space are equiprobable.
$(1)$ Find the probability that the selected number is a multiple of $5.$
$(2)$ Find the probability that the selected number is not a multiple of $5.$
Answer
$(1)\ \frac{4}{17}$
$(2)\ \frac{80}{221}$
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Question 152 Marks
A number is selected from natural numbers $11$ to $100 .$ Find the probability that the selected number contains $9$ as one of the digits.
Answer
$(1)\ \frac{1}{5}$
$(2)\ \frac{4}{5}$
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Question 162 Marks
Find the probability of having both A together in all the arrangements of the letters of the word KATHAN.
Answer
$\frac{17}{90}$
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Question 182 Marks
The weights $($in $kg )$ of $7$ students of a group are $52,58,70,65,50,56$ and $63$ respectively. One student is selected from this group, find the probability that his weight is greater than the average weight of the group.
Answer
$\frac{3}{7}$
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Question 192 Marks
Three coins are tossed simultaneously. Find probability of getting more number of heads than the number of tails.
Answer
$\frac{3}{T}$
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Question 202 Marks
Find the probability of getting at least one head when an unbiased coin is tossed three times.
Answer
$\frac{1}{2}$
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Question 212 Marks
A die is thrown twice. Find the probability of having difference $2$ between the digits obtained on it.
Answer
$\frac{7}{8}$
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Question 222 Marks
Write the rule of multiplication of probability of two events $A$ and $B$ of a sample space. Write the rule of multiplication of probability when two events $A$ and $B$ are independent.
Answer
$\frac{2}{9}$
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Question 232 Marks
Write the rule of addition of probability for two events $A$ and $B$ of a sample space. If these events are mutually exclusive, write the rule of addition of probability.
Answer
સ્વપ્રયત્ન
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2 Marks Each - Statistics STD 12 Commerce Questions - Vidyadip