Mathematics solution NCERT
Class 9 - Chapter 7: The mathematics of maybe: Introduction to Probability
Q1: When a single 6-sided die is rolled, what is the total number of possible outcomes in the sample space?
The possible outcomes when a die is rolled are:
S = {1, 2, 3, 4, 5, 6}
Number of outcomes = 6
Answer: 6 outcomes
Q2: For the following experiments, write down the sample space S.
(i) Rolling a die and tossing a coin together
Coin outcomes: H (Head), T (Tail)
Die outcomes: 1, 2, 3, 4, 5, 6
Sample Space:
S = { (H,1), (H,2), (H,3), (H,4), (H,5), (H,6), (T,1), (T,2), (T,3), (T,4), (T,5), (T,6) }
Total outcomes = 12
(ii) Choosing a random integer between -5 and +5
S = { -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5 }
Total outcomes = 11
(iii) A box containing 5 green and 7 red balls. One ball is drawn at random.
The colour of the ball drawn can be:
S = {Green, Red}
Total outcomes = 2
Q3: Snacks and Drinks at the Village Fair
Given:
- Snacks: Samosa, Pakora, Bhaji
- Drinks: Chai, Lassi
(i) List the sample space of all possible snack and drink combinations.
S = { (Samosa, Chai), (Samosa, Lassi), (Pakora, Chai), (Pakora, Lassi), (Bhaji, Chai), (Bhaji, Lassi) }
Total outcomes = 6
(ii) List the event "Selecting Samosa as a snack".
The snack must be Samosa, while the drink can be Chai or Lassi.
E = { (Samosa, Chai), (Samosa, Lassi) }
Answer:
E = {(Samosa, Chai), (Samosa, Lassi)}
Summary Table
| Question | Answer |
|---|---|
| Q1 | 6 outcomes |
| Q2(i) | 12 outcomes |
| Q2(ii) | {-5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5} |
| Q2(iii) | {Green, Red} |
| Q3(i) | 6 snack-drink combinations |
| Q3(ii) | {(Samosa, Chai), (Samosa, Lassi)} |