# NCERT Class 9 Solutions: Probability (Chapter 15) Exercise 15.1-Part 5

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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