### Video Transcript

If there are three red balls and
nothing else in a bag, is it certain, possible, or impossible that if I pick out a
ball at random, it will be red?

This is quite a wordy question
really. So let’s go through it really
slowly to understand what it’s asking. Firstly, we’ve got a description
and that’s of three red balls and nothing else in a bag. Let’s sketch them. Here are our three balls. And let’s use this circle to
represent the bag that they’re in. Now, there’s a really important
part of that first phrase that we haven’t mentioned yet. And, it’s these two words here. We’re told that there are three red
balls and nothing else in the bag. There aren’t any other colors. There aren’t any other objects. Those three red balls are the only
things in that bag.

Now this question is all about
what’s gonna happen if we pick out a ball at random. When something like this happens at
random, it happens by chance, without any planning or decision-making. If we wanted to pick a ball at
random, maybe we’d close our eyes or, like in the example of this question, we put
the balls inside a bag where we can’t see them. This way, we can’t choose what we
pick. Now the color that we’re asked
about is red.

So this question is asking us,
what’s the chance that we’re going to pick a red ball? And we’re given three possible
answers. Is it certain that we pick a red
ball? Is it possible that we pick a red
ball? Or is it completely impossible that
we pick a red ball? We know that the word ”impossible”
means there’s no chance at all. It’s definitely not going to
happen. Now, if we put our hand into that
bag, we can’t say there’s no chance at all of us pulling out a red ball. We could say it’s impossible we’d
pick out a green ball. It’s impossible we’re going to pull
out a cheeseburger. But we can’t say it’s impossible
we’re going to pull out a red ball. The bag’s full of them.

Let’s get rid of this as a possible
answer. Speaking of possible, is it
possible that we pull out a red ball? We know that when something is
possible, there is a chance of it happening. It might happen; it could
happen. Now this word sounds like it could
be right. It is possible that we pull out a
red ball. But it’s time to come back to those
two words in that first phrase that we said were so important. There are three red balls and
nothing else in a bag. We wouldn’t use the word possible
to describe the chance of us pulling out a red ball. It’s much more than that. It’s absolutely certain because
there’s nothing else in that bag.

If we put our hand in, wiggle it
around, and pull out a ball, it’s going to be red, definitely. And if something is definitely
going to happen, we use the word ”certain.” If you’re not sure about this, try
it. If you don’t have colored balls,
then try three coins that are the same. As long as you don’t put anything
else in your bag, then you’ll see that the chance of you pulling out a red ball or
one of your coins is certain. If there are three red balls and
nothing else in a bag, the chance of us randomly picking out a ball and it being red
is certain.