Mathematics solution NCERT
Class 9 - Chapter 7: The mathematics of maybe: Introduction to Probability
Q1: . Rank the following events on a scale from 0 (Impossible) to
1 (Certain). Label each event: Impossible, less likely, equally likely
(even chance), more likely, certain. Give reasons why you gave
each event its ranking.
(i) The next Monday will come after Sunday.
(ii) It will snow in Mumbai in July.
(iii) An elephant will walk through your classroom today.
(iv) You will greet at least one friend at school tomorrow.
(i) The next Monday will come after Sunday.
Ranking: 1
Label: Certain
Reason: The days of the week always follow the same order. Monday always comes after Sunday.
| Probability | Label |
|---|---|
| 1 | Certain |
(ii) It will snow in Mumbai in July.
Ranking: 0
Label: Impossible
Reason: Mumbai has a tropical coastal climate. July is the monsoon season, and snowfall does not occur there.
| Probability | Label |
|---|---|
| 0 | Impossible |
(iii) An elephant will walk through your classroom today.
Ranking: 0
Label: Impossible
Reason: Under normal circumstances, an elephant cannot enter a classroom. Therefore, the event is considered impossible.
| Probability | Label |
|---|---|
| 0 | Impossible |
(iv) You will greet at least one friend at school tomorrow.
Ranking: 0.8 (approximately)
Label: More Likely
Reason: Students usually meet and greet their friends at school. Although it is not guaranteed, it is very likely to happen.
| Probability | Label |
|---|---|
| 0.8 | More Likely |
Summary Table
| Event | Probability | Label |
|---|---|---|
| The next Monday will come after Sunday. | 1 | Certain |
| It will snow in Mumbai in July. | 0 | Impossible |
| An elephant will walk through your classroom today. | 0 | Impossible |
| You will greet at least one friend at school tomorrow. | 0.8 | More Likely |