Question

If X and Y are two sets such that `n (X)=17, n (Y)= 23` and `n (Xuu Y)= 38` find `n (X nnY)` .

Answer 1

`n(X)=17,n(Y)=23,n(X cupY)=38`
Now, `n(X cupY)=n(X)+n(Y)-n(X cap Y)`
`rArr 38 = 17 + 23 - n(X cap Y)`
`rArr n(X cap Y) = 17 +23 - 38 =2`
Therefore, `n(X cap Y)=2`.