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Chance in Everyday Situations

Maths · Year 3 NAPLAN
Year 3
Lesson Guide
Explanation
There are five chance words and they sit in order. Impossible means it can never happen. Unlikely means it probably will not, but it could. Even chance means it is just as likely to happen as not. Likely means it probably will happen. And certain means it always happens. Impossible and certain are the two ends of the scale, and everything else sits in between them.
Your Turn
Is it certain, likely or impossible that tomorrow comes after today? Check: certain.
Watch Out
Unlikely is not the same as impossible. Unlikely could still happen.
Explanation
Some questions ask which outcome is impossible. Look for the thing that is not there at all. This box has four red, three blue and three green counters, and no yellow, so taking a yellow counter is impossible. Red, blue and green are all possible because they are all in there. Green may be the least likely of the three, but least likely is not the same as impossible, and picking the one there is least of is the classic wrong answer to this question.
Your Turn
A bag has only red and blue marbles. Is taking a green one unlikely or impossible? Check: impossible.
Watch Out
Having only one of something makes it unlikely, not impossible.
Explanation
To compare spinners, count how many parts are the colour you want and how many parts there are altogether. Spinner B has three white parts out of four, which beats A with one out of four, C with two out of four, and D with one out of four. So B is most likely to stop on white. The most parts of the colour you want, out of the same total, wins. But this only works if the parts are the same size, so look at the picture before you count.
Your Turn
A spinner has 5 parts, 4 of them red. Is red likely or unlikely? Check: likely — 4 out of 5.
Watch Out
Count out of the TOTAL. 2 white out of 8 is worse than 2 white out of 4.
Explanation
Here is the hardest chance question on the paper, and it always looks easy. Two boxes both have three red counters. But box A has three red out of five counters, which is more than half, while box B has three red out of ten, which is less than half. So box A gives the better chance even though both have the same number of reds. The number you want is never enough on its own — always ask out of how many. Compare how many you want with how many there are altogether.
Your Turn
2 red out of 4, or 3 red out of 9? Check: 2 out of 4 is half, 3 out of 9 is a third, so 2 out of 4.
Watch Out
The box with the most reds is not always the best chance. Check the total too.
Explanation
Three questions, every time. Is it there at all? If not, it is impossible, and you are done. How many do I want? Count them. And out of how many altogether? Count the whole collection. Then compare: more than half is likely, less than half is unlikely, and exactly half is an even chance. Quiz and exercises now.
Your Turn
5 red out of 10. Likely, unlikely or even chance? Check: exactly half, so an even chance.
Watch Out
Read whether the question wants MOST likely or LEAST likely. They are opposite answers.
📌 Key Points — this lesson in a nutshell
  • Impossible means it can never happen. Certain means it always happens.
  • If a colour is not in the box at all, taking it is impossible.
  • More of something means more likely — but only if the pieces are the same size.
  • To compare two boxes, look at how many you want out of how many there are.
Step 1: Introduction
Step 1 of 5
From impossible to certain impossibleunlikelyeven chancelikelycertain impossible — it can never happen unlikely — it probably will not happen, but it could even chance — just as likely to happen as not likely — it probably will happen certain — it always happens Impossible and certain are the two ends. Everything else sits in between.
Which colour can you never take out? 4 red, 3 blue, 3 green — and no yellow at all Taking a yellow counter is impossible, because there are no yellow counters. Red, blue and green are all possible — they are all in there. Green is the least likely of those three, but it is still possible. For "impossible", look for the thing that is NOT there at all. The wrong answer to this question is always "the one there is least of".
Which is most likely to stop on white? ABCD B is most likely: 3 of its 4 parts are white. A has 1 white out of 4. C has 2 out of 4. D has 1 out of 4. Count how many parts are white and how many parts there are altogether. The most white parts out of the same total wins. This only works if the parts are the same size. Check the picture.
Which box gives the best chance of a red counter? Box A: 3 red out of 5 Box B: 3 red out of 10 Both boxes have 3 red counters — but box A gives the better chance. In box A, 3 out of 5 counters are red: more than half. In box B, 3 out of 10 are red: less than half. The number of reds is not enough on its own. Ask: out of how many? Compare "how many you want" with "how many there are altogether". This is the hardest chance question on the paper, and it always looks easy.
What to ask yourself impossibleunlikelyeven chancelikelycertain Is it there at all?No → impossible. Yes → carry on. How many do I want?Count them. Out of how many?Count the whole collection. More than half is likely. Less than half is unlikely. Exactly half is an even chance. Quiz and exercises now.
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