Question

If n (A) = 7, n (B) = 5, n (A-B) = 3, then
n(AUB) is​

Answer 1

Answer:

8

Step-by-step explanation:

n(A) - n(A-B) =n(A intersection B)

n(AUB)=n(A) + n(B) - n(A intersection B)

= n(A) + n(B)-[n(A) - n(A-B)]

=n(B)+n(A-B)

=5+3

=8

Answer 2

Concept

A set is a clearly defined group of things in mathematics. Set names and symbols begin with a capital letter. According to set theory, a set's constituent parts can be anything, including humans, alphabetic letters, numbers, shapes, variables, etc. Algebra, statistics, and probability all use sets in some capacity.

Given

n(A) = 7

n(B) = 5

n(A₋B) = 3

Find

from the following values derive n(A∪B)

Solution

we know that n(A∩B) = n(A) ₋ n(A₋B)

and n(A U B) = n(A) + n(B) - n(A ∩ B)

hence substitute the given values.

n(A U B) = n(A) + n(B) ₋ [  n(A) ₋ n(A₋B)]

n(A U B) = 7 + 5 ₋ [ 7 ₋ 3]

n(A U B) = 12 ₋4

n(A U B) = 8

hence we get the value of n(A U B) as 8.

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