Question

If A and B are two sets such that n(A)=17, n(B)=23 and n (A U B) = 38, Find n (A - B)

Answer 1

Answer: 15

Step-by-step explanation:

Given : n(AUB)=38 , n(A)=17 & n(B)=23

we know that,

n(AUB) = n(A) + n(B) - n(A ∩ B)

38 =17 + 23 - n(A ∩ B)

38 = 40 - n(A ∩ B)

n(A ∩ B) = 40-38 = 2  

n(A-B) = n(A) - n(A ∩ B)

n(A-B) = 17 - 2 = 15

Answer 2

Answer:

The value of n(A - B) = 15.

Step-by-step explanation:

Given the question is n(A) = 17, n(B) = 23 and n(A∪B) = 38

We have to find the value of n(A - B).

We know that,

n(A∪B) = n(A) +n(B) - n(A∩B)

n(A - B) = n(A) - n(A∩B)

Put the values in this expression, then

38 = 17 + 23 - n(A∩B)

n(A∩B) = 40-38 = 2

Therefore, n(A∩B) = 2.

n(A - B) = n(A) - n(A∩B)

n(A - B) = 17-2 = 15.

Therefore, n(A - B) = 15