Combinatorics & Probability Flashcards
6 cards from real AMC12 practice questions. Tap to flip, then mark Knew It or Still Learning โ missed cards come back until you master them.
Read the first 6 Combinatorics & Probability flashcards as text
In how many ways can 8 people be seated at a round table?
Answer: 5040
Circular arrangements of n people = (n-1)! = 7! = 5040.
What is the probability of rolling a sum of 7 with two standard dice?
Answer: 1/6
The 6 outcomes summing to 7 give P=6/36=1/6.
How many bit strings of length 8 contain exactly three 1s?
Answer: 56
C(8,3)=56.
If a fair die is rolled three times, what is the probability all three rolls are different?
Answer: 5/9
P=(6/6)*(5/6)*(4/6)=120/216=5/9.
How many ordered selections of 2 items from 7 are possible (order matters)?
Answer: 42
P(7,2)=7*6=42.
How many ways can 5 identical balls be distributed into 3 distinct boxes?
Answer: 21
By stars and bars: C(5+3-1,3-1)=C(7,2)=21.