About Probability — Class 9 CBSE

Understand experimental probability through repeated experiments and frequency approach. This topic is part of the CBSE Class 9 mathematics syllabus (chapter: Chapter 15). On this page you can practice 62 questions across three difficulty levels — 20 easy, 20 medium, and 22 hard — each with a visual step-by-step solution, plus a timed 37-question mastery test with a live leaderboard. Worked examples and sample questions from the topic are below.

What you'll learn in Probability

• Introduction to Probability: Chance and Certainty
• Experimental Probability: Learning from Experience
• Applying Experimental Probability: Diverse Scenarios
• Advanced Applications: Probability from Large Datasets
• Summary and Practice: Mastering Probability

Interactive lesson · about 15 minutes · checkpoint question after every unit

Probability — solved examples for Class 9 CBSE

Practice questions on Probability

1. Q1.easy

   Which of the following values cannot be the probability of an event?

   1. A)A) 0.7
   2. B)B) 1/2
   3. C)C) 1.5
   4. D)D) 0
   Show answer

   Answer: C) 1.5

   Hint: Remember that the probability of any event must always lie within a specific numerical range.

2. Q2.easy

   If P(E) is the probability of an event E, what is the probability of the event 'not E'?

   1. A)A) 1 - P(E)
   2. B)B) 1 / P(E)
   3. C)C) P(E)
   4. D)D) 0
   Show answer

   Answer: A) 1 - P(E)

   Hint: Consider that an event either happens or it doesn't. The sum of these two possibilities must cover all outcomes.

3. Q3.easy

   A coin is tossed 200 times. The outcomes are recorded as follows: Heads: 110 times, Tails: 90 times. What is the experimental probability of getting a Head?

   1. A)A) 9/20
   2. B)B) 11/20
   3. C)C) 1/2
   4. D)D) 11/9
   Show answer

   Answer: B) 11/20

   Hint: To find the experimental probability, you need the number of times the desired event occurred divided by the total number of trials.

4. Q4.medium

   Which of the following values cannot be the probability of an event?

   1. A)0.5
   2. B)2/3
   3. C)1.5
   4. D)0
   Show answer

   Answer: 1.5

   Hint: Remember that the probability of any event must always lie between 0 and 1, inclusive.

5. Q5.medium

   A die is rolled 100 times, and the outcomes are recorded as follows:
   Outcome | Frequency
   --------|----------
   1 | 15
   2 | 18
   3 | 20
   4 | 17
   5 | 16
   6 | 14
   What is the experimental probability of getting an even number?

   1. A)18/100
   2. B)49/100
   3. C)51/100
   4. D)50/100
   Show answer

   Answer: 49/100

   Hint: An even number can be 2, 4, or 6. Sum the frequencies for these outcomes.

6. Q6.medium

   A survey of 200 students was conducted to find out their favorite subject. The results are shown in the table:
   Subject | Number of Students
   ------------|-------------------
   Mathematics | 60
   Science | 50
   English | 45
   Social Science| 30
   Hindi | 15
   What is the experimental probability that a randomly chosen student's favorite subject is either Mathematics or Science?

   1. A)60/200
   2. B)50/200
   3. C)110/200
   4. D)110/100
   Show answer

   Answer: 110/200

   Hint: Add the number of students who prefer Mathematics and Science, then divide by the total number of students surveyed.

7. Q7.hard

   A bag contains 200 balls of three colors: Red, Blue, and Green. The experimental probability of drawing a Red ball is 0.25. The number of Blue balls is 30 more than the number of Green balls. What is the number of Green balls in the bag?

   1. A)40
   2. B)50
   3. C)60
   4. D)70
   Show answer

   Answer: 60

   Hint: First, use the probability of drawing a Red ball to find the number of Red balls. Then, set up an equation for the remaining balls to find the count of Green balls.

8. Q8.hard

   Ravi was calculating the experimental probabilities for two events, E and F, in an experiment. He stated that P(E) = 1.15 and P(F) = -0.05. Which of the following statements correctly identifies the fundamental error in Ravi's calculations?

   1. A)The sum of probabilities for all events must be 1.
   2. B)The probability of any event must be between 0 and 1, inclusive.
   3. C)Experimental probability cannot be a decimal number.
   4. D)Only theoretical probabilities can be less than 0 or greater than 1.
   Show answer

   Answer: The probability of any event must be between 0 and 1, inclusive.

   Hint: Recall the fundamental properties of probability, specifically the range of values a probability can take.

9. Q9.hard

   Three unbiased coins are tossed simultaneously 200 times. The observed frequencies of outcomes are: 3 Heads: 25 times, 2 Heads: 75 times, 1 Head: 80 times, 0 Heads: 20 times. What is the experimental probability of getting at most one head OR exactly three heads?

   1. A)1/8
   2. B)1/2
   3. C)5/8
   4. D)3/4
   Show answer

   Answer: 5/8

   Hint: Identify the number of trials for 'at most one head' and 'exactly three heads'. Since these are distinct outcomes, you can sum their frequencies.

These are 9 of the 62 questions available for Probability. Start practicing above to unlock visual solutions, AI coaching, and the topic leaderboard — completely free.