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12th CBSE

IMPORTANT

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A shopkeeper sells three types of flower seeds $A_{1}, A_{2}$ and $A_{3}$ . They are sold as a mixture where the proportions are $4 : 4 : 2$ respectively. The germination rates of the three types of seeds are $45 %, 60 %$ and $35 %$ . Calculate the probability that it is of the type $A_{2}$ given that a randomly chosen seed does not germinate (correct up to three decimal places).

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Important Questions on Probability

HARD

12th CBSE

IMPORTANT

NCERT Exemplar Mathematics - Class 12>Chapter 13 - Probability>EXERCISE>Q 44

A letter is known to have come either from TATA NAGAR or from CALCUTTA. On the
envelope, just two consecutive letter TA are visible. What is the probability that the letter came from TATA NAGAR.

HARD

12th CBSE

IMPORTANT

NCERT Exemplar Mathematics - Class 12>Chapter 13 - Probability>EXERCISE>Q 45

There are two bags, one of which contains

3

black and

4

white balls while the other contains

4

black and

3

white balls. A die is thrown. If it shows up 1 or

3

, a ball is taken from the

1

st bags but it shows up any other number, a ball is chosen from the second bag. Find the probability of choosing a black ball.

HARD

12th CBSE

IMPORTANT

NCERT Exemplar Mathematics - Class 12>Chapter 13 - Probability>EXERCISE>Q 46

There are three urns containing

2

white and

3

black balls,

3

white and

2

black balls, and

4

white and

1

black balls, respectively. There is an equal probability of each urn being chosen. A ball is drawn at random from the chosen urn and it is found to be white. Find the probability that the ball drawn was from the second urn.

HARD

12th CBSE

IMPORTANT

NCERT Exemplar Mathematics - Class 12>Chapter 13 - Probability>EXERCISE>Q 47

By examining the chest

X

ray, the probability that TB is detected when a person is actually suffering is

0.99 .

The probability of a healthy person diagnosed to have TB is

0.001

. In a certain city,

1

1000

people suffers from TB. A person is selected at random and is diagnosed to have TB. What is the probability that he actually has TB?

HARD

12th CBSE

IMPORTANT

NCERT Exemplar Mathematics - Class 12>Chapter 13 - Probability>EXERCISE>Q 48

An item is manufactured by three machines

A, B

and

C

. Out of the total number of items manufactured during a specified period,

50 %

are manufactured on

A, 30 %

B

and

20 %

C

2 %

of the items produced on

A

and

2 %

of items produced on

B

and

3 %

of items produced on

C

are defective. All the items are stored at one godown. One item is drawn at random and is found to be defective. What is the probability that it was manufactured on machine

A

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12th CBSE

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NCERT Exemplar Mathematics - Class 12>Chapter 13 - Probability>EXERCISE>Q 52

A bag contains

(2 n + 1)

coins. It is known that

n

of these coins have a head on both sides whereas the rest of the coins are fair. A coin is picked up at random from the bag and is tossed. If the probability that the toss results in a head is

\frac{31}{42},

determine the value of

n

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12th CBSE

IMPORTANT

NCERT Exemplar Mathematics - Class 12>Chapter 13 - Probability>EXERCISE>Q 53

Two cards are drawn successively without replacement from a well shuffled deck of cards. Find the mean and standard deviation of the random variable

X

where

X

is the number of aces.

HARD

12th CBSE

IMPORTANT

NCERT Exemplar Mathematics - Class 12>Chapter 13 - Probability>EXERCISE>Q 54

A die is tossed twice. A 'success' is getting an even number on a toss. Find the variance of the number of successes.

Important Questions on Probability

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