P and Q are non empty sets such that n(P)=10 and n(Q)= 6. Find the smallest possible value of n(PUB).

Answer 1

n(P) =10, n(Q) = 6, n(PUB) = ?

smallest n(B) = 0, the null set, B={ }

then n(PUB) = n(P) = 0

0 < n(B) < infinity

no limit to how large B is

but it can't be less than zero

UNLESS there's some reason to allow negative numbers

such as + means credits in accounting and - means debit or debts

then there's no limit to how small B can be, such as the national debt in the US

but in a Venn diagram, the numbers are all positive or zero. This looks like a Venn diagram type problem