Question

if W = {positive integers} and subset Z = {positive integers divisible by 5}, what is Z′?

{1, 2, 3, 4, …}

{ }

{5, 10, 15, 20, …}

{1, 2, 3, 4, 6, 7, 8, 9, 11, 12, 13, 14, 16, …}

Answer 1

{5, 10, 15, 20, …}

Answer 2

{5, 10, 15, 20, …}

Answer 3

Z' stands for the set of everything in set W, but stuff that is NOT in set Z. So this means that we start with set W

W = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ...}

and then we kick out all of the multiples of 5 like so

Z' = {1, 2, 3, 4, 6, 7, 8, 9, 11, 12, ...}


So the answer is choice D)