Question

Let the Universal Set, S, have 203 elements. A and B are subsets of S. Set A contains 98 elements and Set B contains 81 elements. If the total number of elements in either A or B is 173, how many elements are in A but not in B?

Answer 1

92

Explanation:

it is given that total number of elements =203

set A contains 98 that is A=98

set B contain 81 elements B=81

It is given that either A or B is 173

we know the formula

`n\left ( A\cup B \right )=n(A)+n(B)-n(A\cap B)`

173=98+81 -
`n\left ( A\cap B \right )`

`n\left ( A\cap B \right )` = 6

so the elements in A but not B =98-6=92