NCERT Class 9 Solutions: Probability (Chapter 15) Exercise 15.1-Part 3

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Calculation of probability with example

Calculation of Probability with Example

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Q-6 Following table shows the performance of two sections of students in Mathematics test of 100 marks.

Mathematics test marks of 100 students are given

Mark

Number of student

7

10

10

20

20

15

8

Total

90

I. Find the probability that a student obtained less than in the mathematics test.

II. Find the probability that a student obtained marks or above.

Solution:

Total numbers of students = 90

Solution I:

Numbers of students obtained less than 20% in the mathematics test

Required probability

Solution II:

Numbers of student obtained marks 60 or above

Required probability

Q-7 To know the opinion of the students about the subject statistics, a survey of 200 students was conducted. The data is recorded in the following table.

Distribution of opinion

Opinion

Number of students

Like

Dislike

135

65

Find the probability that a student chosen at random

I. Like statistics

II. Does not like it.

Solution:

Total numbers of students

Solution I:

Numbers of students who like statistics

Required probability

Solution II:

Numbers of students who does not like statistics

Required probability