Probability
0/10 problems solved
Formulas & 30-Second Shortcut Tricks
Formulas
- P(E) = favourable outcomes / total outcomes
- P(not E) = 1 − P(E)
- Independent events: P(A and B) = P(A)·P(B)
- Two dice: 36 outcomes; a deck: 52 cards, 4 suits, 13 each, 12 face cards
Shortcuts
- "At least one" ⇒ 1 − P(none).
- Dice sum table: sum 7 has 6 ways (max); sum 2 or 12 has 1 way each.
Practice problems
Two dice are thrown. What is the probability that the sum is 6?
A bag has 4 red and 2 blue balls. Two are drawn without replacement. What is P(both red)?
A coin is tossed 2 times. What is the probability of getting at least one head?
Two dice are thrown. What is the probability that the sum is 7?
A bag has 6 red and 5 blue balls. Two are drawn without replacement. What is P(both red)?
A coin is tossed 2 times. What is the probability of getting at least one head?
Two dice are thrown. What is the probability that the sum is 5?
A bag has 4 red and 4 blue balls. Two are drawn without replacement. What is P(both red)?
A coin is tossed 4 times. What is the probability of getting at least one head?
Two dice are thrown. What is the probability that the sum is 5?
Probability Speed Test
1 minute per question. Use the palette to jump around; you'll see time spent on every question at the end.