A scale of chance
Place the probability on the line from 0 (impossible) to 1 (certain).
Why it works
Closer to 1 → more likely.
Data & Probability · Probability · 3.4
How likely?
Probabilities run from 0 to 1. A probability of 0 is impossible, 1 is certain, ½ is even chance; below ½ is unlikely and above ½ is likely. The number tells you where the event sits on that scale.
See it work.
Watch the method
How likely?
0 = impossible, ½ = even, 1 = certain.
Find the likelihood of: .
1
Add the values
Find the total of every value in the set.
2
Divide by how many
The mean is the total divided by the number of values.
The idea underneath.
From easy to tricky.
An event has probability 2/10. It is…
1
Answer
Unlikely
An event has probability 0/6. It is…
1
Answer
Impossible
An event has probability 0/8. It is…
1
Answer
Impossible
Where students slip.
Trap
Calling ⅓ likely.
Fix
Below ½ is unlikely.
Trap
Thinking probability can exceed 1.
Fix
It ranges only from 0 to 1.
Test yourself.
The Test
12 problems across three tiers. Auto-graded on submit. Hints and a full walkthrough on every question. Your work is saved on this device — sign in to keep it across devices.
0/12Answered
How to answerType just the value. Formatting won't trip you up — we ignore spaces, capital letters, commas, and subscript style, so
t₁ = 5, d = 3 and t1=5,d=3 both count. For a list of numbers, separate them with commas (e.g. 3, 10, 17).Core
Core (4)
C1
An event has probability 2/6. It is…
Need a hint?
- Compare the probability to ½.
- 0 is impossible; 1 is certain.
C2
An event has probability 8/8. It is…
Need a hint?
- Compare the probability to ½.
- 0 is impossible; 1 is certain.
C3
An event has probability 0/8. It is…
Need a hint?
- Compare the probability to ½.
- 0 is impossible; 1 is certain.
C4
An event has probability 0/10. It is…
Need a hint?
- Compare the probability to ½.
- 0 is impossible; 1 is certain.
Apply
Apply (4)
A1
An event has probability 8/8. It is…
Need a hint?
- Compare the probability to ½.
- 0 is impossible; 1 is certain.
A2
An event has probability 0/8. It is…
Need a hint?
- Compare the probability to ½.
- 0 is impossible; 1 is certain.
A3
An event has probability 8/8. It is…
Need a hint?
- Compare the probability to ½.
- 0 is impossible; 1 is certain.
A4
An event has probability 0/6. It is…
Need a hint?
- Compare the probability to ½.
- 0 is impossible; 1 is certain.
Extension
Extension (4)
E1
An event has probability 10/10. It is…
Need a hint?
- Compare the probability to ½.
- 0 is impossible; 1 is certain.
E2
An event has probability 5/8. It is…
Need a hint?
- Compare the probability to ½.
- 0 is impossible; 1 is certain.
E3
An event has probability 10/10. It is…
Need a hint?
- Compare the probability to ½.
- 0 is impossible; 1 is certain.
E4
An event has probability 5/6. It is…
Need a hint?
- Compare the probability to ½.
- 0 is impossible; 1 is certain.