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(male narrator) So given these two sets here,
what is the cardinality of Set B?
Now cardinality is just a fancy way of saying,
"How many things are in the set?"
In other words, what's the count of the set?
Um...and we'll often represent that using the sort of n of B.
This says the number of elements in Set B.
Or sometimes you'll see absolute value
or size of B rep... uh...used in set,
but we're gonna go ahead and use this.
So the number of elements in Set B.
All we have to do is count how many elements there are.
There are 1, 2, 3, 4 of them,
so the cardinality of Set B is just 4.
Okay?
What is the cardinality of A union B?
Well, in order to answer that,
let's go ahead and find the union.
So we need to union these two sets.
So we've got everything from A...
and now we're gonna combine that with everything from B.
We already have 2.
We already have 4.
We already have 6.
We just need 8.
And this set has 1, 2, 3, 4, 5, 6, 7 elements,
so the number of elements in A union B is 7.
Now for the intersection...
let's see, the intersection of the two is...
let's see, we got 2, 4, and 6 in both sets,
so the number of elements in the intersection is 3.
So last question here is unrelated to those sets.
It says, what is the cardinality of Set P,
which is the set of English names
for the months of the year?
So...as you probably know,
there are, uh...12 months in the year.
So the number of month names...
or actually, I guess it should say,
the number of elements in Set P is 12.
There are 12 names for the months of the year.