Probability Basics
Roll one fair die. List the sample space.
{1,2,3,4,5,6}
Flip a coin then roll a die. How many outcomes?
12
Roll a fair die. P(get a 4).
1/6
Mean of 2, 4, 6, 8.
5
Which center is less affected by outliers: mean or median?
Median
Toss two coins once. List the sample space.
{HH, HT, TH, TT}
Choose cone or cup (2) and flavor chocolate or vanilla (2). How many choices?
Roll a fair die. P(even).
1/2
Median of 3, 7, 9, 2, 5.
5
Two classes have the same mean 75. Class A median 75; Class B median 68. Which likely has some very high scores?
Class B
In “toss two coins,” is “at least one head” an outcome or an event?
Event
Make a 2-letter code from A,B,C without repetition. How many codes?
6
Toss two coins. P(exactly one head).
1/2
Mode of 4, 4, 5, 6, 6, 6, 7.
6
If the median score is 12, what can you say about how many scores are at least 12?
At least half
From S={1,2,3,4,5,6}, let E = “even.” List E.
{2,4,6}
Choose a main (3), a drink (4), and a dessert (2). How many meals?
24
Bag has 5 red, 3 blue, 2 green marbles. Draw one. P(blue).
3/10
Four numbers have mean 13. Three are 10, 12, 15. Find the fourth.
15
Set X: mean=50, median=50
Set Y: mean=50, median=62
Which set likely has some very low scores pulling the mean down?
Set Y
State the difference between a sample space and an event (one sentence).
Sample space: all outcomes; event: a set of outcomes.
Roll two dice. How many outcomes in the sample space?
36
Form a 2-digit number from digits 1–5 without repetition (all equally likely). P(number is odd).
3/5
Data: 6, 8, 8, 9, 10, 12. Add 20. What is the new mean?
73/7 (≈10.43)
Two stores have median weekly sales 100k. Store X mean=150k; Store Y mean=110k. Which likely has more extreme high days?
Store X