Test Index

JAMB Mathematics 2015 Paper

Question : 5

Total: 61

Solution:

Concept:

The size of a union of two sets is found by adding their individual sizes and subtracting the size of their intersection.

Explanation:

We are given

n(X) = 15

n(Y) = 12

, and

n(X \cap Y) = 7

Use the formula:

n(X \cup Y) = n(X) + n(Y) - n(X \cap Y)

Substitute the given values:

n(X \cup Y) = 15 + 12 - 7

n(X \cup Y) = 20

Answer:

n(X \cup Y) = 20

, so the correct option is D.

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