Question

Find D E.
D: {adults between the ages of 30 and 35}
E: {a person who is 45 years old}

{ }
{adults between the ages of 30 and 35 and a person who is 45 years old}
{a person who is 45 years old}
{adults between the ages of 30 and 45}

Answer 1

Intersection

Answer 2

Sometimes there will be no intersection at all. In that case we say the answer is the "empty set" or the "null set" {}

Answer 3

Ask yourself, Is there anyone in both sets? Can you be between the ages of 30 and 35 AND ALSO 45 years old? No, so the answer is that nobody is in both sets, therefore the answer is the empty set, {}.