Free practice on Sets and Logic for Class 3, following the Cameroon primary school curriculum (English subsystem). Every answer is explained, so a parent who is not sure of the answer can still help.
A set is a collection of things that belong together. Think of a basket of mangoes — all the mangoes in the basket make one set!
Set of fruits: mango · pawpaw · banana · orange · pineapple
The universal set is the big group that contains everything we are talking about. A subset is a smaller group inside it. If all the pupils in your school are the universal set, then the pupils in Class 3 are a subset.
A finite set has a number you can count to the end. The pupils in your class — you can count them! An infinite set goes on forever, like the set of all counting numbers: 1, 2, 3, 4 … it never stops.
| Finite set | Infinite set |
|---|---|
| Days of the week (7) | Counting numbers (1, 2, 3 …) |
| Fingers on your hand (5) | Even numbers (2, 4, 6 …) |
Equal sets have exactly the same members. Equivalent sets have the same number of members but different things inside. Set A = {cat, dog} and Set B = {cat, dog} are equal. Set C = {pen, book} is equivalent to A because both have 2 members.
| Equal sets | Equivalent sets |
|---|---|
| {cat, dog} = {cat, dog} | {cat, dog} ↔ {pen, book} |
| Same members | Same size, different members |
We use curly brackets { } to write a set. The symbol ∈ means 'belongs to' and ∉ means 'does not belong to'. If A = {1, 2, 3} then 2 ∈ A but 5 ∉ A.
| Symbol | Meaning |
|---|---|
| { } | Set brackets |
| ∈ | Belongs to |
| ∉ | Does not belong to |
| ⊂ | Is a subset of |
Which set is a set of fruits?
Answer: A. {mango, pawpaw, orange}
Mango, pawpaw and orange are all fruits.
A set with nothing inside is called:
Answer: B. an empty set
The empty set has no members at all.
{1, 2, 3} and {1, 2, 3} have exactly the same members. They are:
Answer: A. equal sets
Equal sets have exactly the same members.
The set of ALL the whole numbers goes on forever. It is:
Answer: B. an infinite set
An infinite set never ends.
How many members are in the set {2, 4, 6, 8}?
Write your answer, then check below.
Answer: 4
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