Combinatorics and Probability Flashcards
6 cards from real AMC12 practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Combinatorics and Probability flashcards as text
What is C(8, 3)?
Answer: 56
C(8, 3) = 8 × 7 × 6 / (3 × 2 × 1) = 336/6 = 56.
In how many ways can the letters of 'LEVEL' be arranged?
Answer: 30
'LEVEL' has 5 letters with L repeated twice and E repeated twice, so arrangements = 5!/(2!2!) = 30.
What is the probability that a card drawn from a standard 52-card deck is a face card or a heart?
Answer: 11/26
By inclusion-exclusion: (12 + 13 − 3)/52 = 22/52 = 11/26.
If P(A) = 0.4 and P(B) = 0.3 and A, B are independent, what is P(A ∩ B)?
Answer: 0.12
For independent events, P(A ∩ B) = P(A) × P(B) = 0.4 × 0.3 = 0.12.
How many ways can 3 people be seated in a row of 5 chairs?
Answer: 60
P(5, 3) = 5!/(5−3)! = 5 × 4 × 3 = 60.
A fair coin is flipped 5 times. What is the probability of getting exactly 3 heads?
Answer: 5/16
C(5, 3) × (1/2)⁵ = 10/32 = 5/16.