Question

If AuB=20,AnB=,7 andthe number of element B is twice that of A. Then find the number of element in A and in B

Answer 1

number of elements in A = 7

number of elements in B = 14

Explanation:

A U B = 20

A ∩ B = 7

let x be the number of elements in A

as per given:

number of elements in B = 2x

x + 2x = 20

3x = 20

x = 20/3 = 6.7 = 7

2x = 2(7) = 14

thus,

number of elements in A = 7

number of elements in B = 14