00:01
For this problem, we were given four options and we need to identify which one does not represent a discrete random variable.
00:09
Now, to answer that question, we need to understand what a discrete random variable is.
00:14
And so, let me write the definition.
00:21
Okay, so a discrete random variable x takes a fixed set of possible values with gaps, between.
01:00
Okay.
01:02
Now the key is gaps, gaps between.
01:06
Now the answer is going to be a.
01:09
And so to understand what a random variable is, let's look at why the answer is not b, c, and d.
01:14
Now, if you ask someone the number of students in a classroom, the answer could be 30, maybe 27 or even 44, right? we can agree that the answer can be any whole number, but the answer cannot be.
01:30
Be a decimal such as if someone tells you 26 .72 students in a classroom that doesn't make sense.
01:37
So we can say that this right here is not a possible answer.
01:41
Any decimal is not going to be a possible answer.
01:44
So part b has gaps in between the possible values, meaning the decimals.
01:51
Now when you look at c, the number of credit cards used by a person, once again, we expect the answer to be a whole number, such as three, seven, seven, right, maybe five...