Q.1. In a cricket match, a batswoman hits a boundary 6 times out of 30 balls she plays. Find the probability that she did not hit a boundary.

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Q.9. Activity : Note the frequency of two-wheelers, three-wheelers and four-wheelers going past during a time interval, in front of your school gate. Find the probability that any one vehicle out of the total vehicles you have observed is a two-wheeler.

Ans: During a time, interval of 5 minutes, total 30 vehicles going in which

Two wheelers = 15

Three wheelers = 5

Four wheelers = 10

∴ P (Two-wheeler) = $\frac{No.\,\,of\,\,two\,\,wheelers}{Total\,\,number\,\,of\,\,Vehicles}=\frac{15}{30}=\frac{1}{2}$

Q.10. Activity : Ask all the students in your class to write a 3-digit number. Choose any student from the room at random. What is the probability that the number written by her/him is divisible by 3? Remember that a number is divisible by 3, if the sum of its digits is divisible by 3.

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Q.12. In Q.5, Exercise 14.2, you were asked to prepare a frequency distribution table, regarding the concentration of Sulphur dioxide in the air in parts per million of a certain city for 30 days. Using this table, find the probability of the concentration of Sulphur dioxide in the interval 0.12 – 0.16 on any of these days.

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Q.13. In Q.1, Exercise 14.2, you were asked to prepare a frequency distribution table regarding the blood groups of 30 students of a class. Use this table to determine the probability that a student of this class, selected at random, has blood group AB.

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NCERT Solutions For Class 9 Maths Chapter 15 Probability (All Exercises)