Video: Determining Certain, Likely, Unlikely, or Impossible Events

Kathryn Kingham

If the spinner is spun once, determine whether it is certain, likely, unlikely, or impossible that the pointer stops on a number that is a multiple of 3.

03:15

Video Transcript

If the spinner is spun once, determine whether it is certain, likely, unlikely, or impossible that the pointer stops on a number that is a multiple of three.

Here, we’re investigating the likelihood of the pointer stopping on a number that is a multiple of three. Our first step here, it needs to be to determine how many multiples of three are found on our spinner. Is 23 a multiple of three? In other words, can we divide 23 by three? No, 23 is not a multiple of three. Is 24 a multiple of three? 24 divided by three is eight. That means 24 is a multiple of three. We’ll go ahead and circle 24.

Is eight a multiple of three or divisible by three? No. Next up is 10. Is 10 a multiple of three? It is not. Is 19 a multiple of three? No. Finally, 11, is 11 a multiple of three? It’s not.

On our spinner, we have six numbers and only one of them is a multiple of three. One out of our six options is a multiple of three. Now, we need to know is it certain, likely, unlikely, or impossible that the pointer will stop on a number that is a multiple of three.

If it were going to be certain, we would need all six of these numbers to be multiples of three. We would need six out of six. So we know it’s not certain. But is it impossible? Is it impossible that where it lands is a multiple of three? No, if it were going to be impossible, then we would have zero out of six numbers being a multiple of three.

Now, we’re left with two choices: is it likely or unlikely that our spinner is going to land on a multiple of three? In this case, is it likely or unlikely that our spinner will land on 24? One out of six chances is that it will land on 24. But five out of six chances is that it will not land on 24.

If we were to describe this event with one of these four words, the best word to use to describe it is unlikely. It is unlikely that our spinner will land on 24.

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