# NCERT Class 9 Solutions: Probability (Chapter 15) Exercise 15.1-Part 5 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Q-12 A study was conducted to find out the concentration of sulphur dioxide in the air parts per million (ppm) of a certain city. The data obtained for 30 days is as follows:

Using this table, find the probability of the concentration of sulphur dioxide in the interval on any of these days.

Solution:

Total numbers of day՚s data recorded

Numbers of days in which sulphur dioxide in the interval

Required probability

Q-13 The blood groups of students of class VIII are recorded as follows:

A, B, O, O, AB, O, A, O, B, A, O, B, A, O, O, A, AB, O, A, A, O, O, AB, B, A, O, B, A, B, O.

Using this table to determine the probability that a student of this class, selected at random, has blood group AB.

Solution:

Total numbers of students

Numbers of students having blood group AB

Required probability