CBSE Class 10-Mathematics: Chapter – 15 Probability Part 4 (For CBSE, ICSE, IAS, NET, NRA 2022)

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5 Mark Questions

Question 17:

In a musical chair same the person playing the music has been advised to stop playing the music at any time within 2 minutes after she starts playing. What is the probability that the music will stop within the half minute after starting.

Answer:

Here the possible outcomes are all the numbers between .

This is the portion of the number line from as shown in figure.

Let A be the event that ‘the music is stopped within the first half minute.’ Then, outcomes favourable to event A are all points on the number line from

The Total Number of Outcomes

The total number of outcomes are the points on the number line from i.e..) to 2.

Question 18:

A jar contains marbles each of which is blue. Green or white. The probability of selecting a blue marble at random from the jar is and the probability of selecting a green marble at random is . How many white marbles does the jar contain?

Answer:

Let there be blue, g green and w white marbles in the marbles in the jar. Then, 4

It is given that the probability of selecting a blue marbale is .

We have.

Substituting the values of b and in (i) , we get

1 Mark Questions

Question 1:

Complete the statements:

(i) Probability of event Probability of event “not E” ________

(ii) The probability of an event that cannot happen is ________. Such an event is called ________.

(iii) The probability of an event that is certain to happen is ________. Such an event is called ________.

(iv) The sum of the probabilities of all the elementary events of an experiment is ________.

(v) The probability of an event is greater than or equal to ________ and less than or equal to ________.

Answer:

(i)

(ii) , impossible event.

(iii) , sure or certain event

(iv)

(v)

Question 2:

Which of the following cannot be the probability of an event:

(A)

(B)

(C)

(D)

Answer:

(B) Since the probability of an event E is a number P (E) such that

cannot be the probability of an event.

Question 3:

If , what is the probability of ‘not E’ ?

Answer:

Since

Question 4:

It is given that in a group of students, the probability of students not having the same birthday is . What is the probability that the students have the same birthday?

Answer:

Let E be the event of having the same birthday

But

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