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.

SOLUTION

(i) The next Monday will come after Sunday

The days of the week always follow the same order:
Sunday→ Monday → Tuesday ...
Monday always comes after Sunday.
Probability = 1
The event is certain because it will definitely happen every week.

(ii) It will snow in Mumbai in July

Mumbai has a hot and humid climate in July, so snowfall does not occur there in July.
Probability = 0
It is an impossible event as Mumbai is not cold enough for snowfall in July.

(iii) An elephant will walk through your classroom today

Elephants are not usually found in schools or classrooms. It is extremely unlikely, though not impossible in usual situations.
Probability ≈ 0.1
The event is less likely to occur. Such an event almost never happens in everyday life.

(iv) You will greet at least one friend at school tomorrow

Students usually meet and greet friends at school. So this is very likely to happen.
Probability ≈ 0.8
This event is more likely to occur because one normally interacts with friends at school.

Concept Note

Events that definitely happen have probability 1 and are called certain.
Events that cannot happen have probability 0 and are impossible.
Events with small possibility are less likely.
Events with large possibility are more likely.