Union, intersection and difference of sets with excluded borns

Question

Basic stuff...

$[1, 5] ∩ [4, 5[$ -> What is the good answer ? is it $[4, 5[$ or $[4, 5]$ ?

Correct me if i'm wrong:

$A = [1,5]$ includes {$1; 1.34; 3.23; 4; 5$}

$B = [4, 5[$ includes {$4.32; 4.44; 4.99$}

So if I intersect A and B, I get all value between $[4, 5[$

Am I right ? Also if it is an A union B, would it be [1, 5] ?

Thanks

Answer 1

Yes you are right. But there are more numbers in $A$ and $B$ than what you listed.