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NCERT Class 9 Mathematics Exercise Set 7.3 Solutions: The Mathematics of Maybe: Introduction to Probability
AI-written, checked on 23 Oct 2026
Solutions written by Shishya, checked — not the board's official answers
Step-by-step working for every question of Exercise Set 7.3 in NCERT's Class 9 Mathematics book, chapter “The Mathematics of Maybe: Introduction to Probability”, written by Shishya. Each question is in our own short words; open the NCERT chapter for the exact wording and figures.
How these were checked: the solutions were drafted with AI and then read and corrected on 23 Oct 2026. Every numerical final answer is recomputed from the question's own numbers by a calculator check that runs before each release; proofs and explanations were read, not machine-checked. The NCERT textbook is the authority — if something here disagrees with it, follow the book.
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Ex 7.3 Q1
How many outcomes are in the sample space when one six-sided die is rolled?
- A standard die has six faces numbered 1, 2, 3, 4, 5, and 6.
- When the die is rolled, any one of these six numbers can appear on the top face.
- Therefore, the total number of possible outcomes is 6.
Answer: 6
Ex 7.3 Q2
Write the sample space S: (i) a die is rolled and a coin is tossed together; (ii) an integer is chosen at random between −5 and 5; (iii) one ball is drawn from a box of 5 green and 7 red balls.
- (i) A die has 6 faces (1 to 6) and a coin has 2 outcomes (H, T).
- (i) The sample space S is the set of all pairs: {1H, 1T, 2H, 2T, 3H, 3T, 4H, 4T, 5H, 5T, 6H, 6T}.
- (i) The number of outcomes n(S) is 6 × 2 = 12.
- (ii) Reading "between −5 and 5" as not including −5 and 5 themselves:
- (ii) The integers strictly between −5 and 5 are −4, −3, −2, −1, 0, 1, 2, 3, 4.
- (ii) The sample space S is {−4, −3, −2, −1, 0, 1, 2, 3, 4}.
- (ii) If −5 and 5 are included as well, S = {−5, −4, −3, −2, −1, 0, 1, 2, 3, 4, 5}.
- (iii) The box contains only green and red balls.
- (iii) Drawing one ball results in either a green ball or a red ball.
- (iii) The sample space by colour is S = {Green, Red}. The two outcomes are not equally likely (5 of the 12 balls are green, 7 are red).
Answer: (i) n(S) = 12; (ii) {−4, −3, −2, −1, 0, 1, 2, 3, 4}; (iii) {Green, Red}
Ex 7.3 Q3
At a fair a person picks one snack (Samosa, Pakora or Bhaji) and one drink (Chai or Lassi). (i) List the sample space of snack-drink choices. (ii) List the event "Samosa is the snack".
- (i) The possible snacks are Samosa, Pakora, and Bhaji.
- (i) The possible drinks are Chai and Lassi.
- (i) The sample space consists of all 3 × 2 = 6 possible pairs of snack and drink.
- (i) The sample space is {(Samosa, Chai), (Samosa, Lassi), (Pakora, Chai), (Pakora, Lassi), (Bhaji, Chai), (Bhaji, Lassi)}.
- (ii) The event 'Samosa is the snack' includes only the pairs where the first item is Samosa.
- (ii) The outcomes in this event are (Samosa, Chai) and (Samosa, Lassi).
Answer: (i) 6 outcomes; (ii) (Samosa, Chai), (Samosa, Lassi)
Other exercises in this chapter
- Exercise Set 7.1 — 1 questions
- Exercise Set 7.2 — 6 questions
- Exercise Set 7.4 — 2 questions
- End-of-chapter exercises — 16 questions
← The Mathematics of Maybe: Introduction to Probability: notes, practice and all exercises
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