Math 8.1

Probability Basics

100

Roll one fair die. List the sample space.

{1,2,3,4,5,6}

200

Toss two coins once. List the sample space.

{HH, HT, TH, TT}

300

In “toss two coins,” is “at least one head” an outcome or an event?

Event

400

From S={1,2,3,4,5,6}, let E = “even.” List E.

{2,4,6}

500

State the difference between a sample space and an event (one sentence).

Sample space: all outcomes; event: a set of outcomes.

Counting Outcomes

100

Flip a coin then roll a die. How many outcomes?

12

200

Choose cone or cup (2) and flavor chocolate or vanilla (2). How many choices?

4

300

Make a 2-letter code from A,B,C without repetition. How many codes?

6

400

Choose a main (3), a drink (4), and a dessert (2). How many meals?

24

500

Roll two dice. How many outcomes in the sample space?

36

Simple Probability

100

Roll a fair die. P(get a 4).

1/6

200

Roll a fair die. P(even).

1/2

300

Toss two coins. P(exactly one head).

1/2

400

Bag has 5 red, 3 blue, 2 green marbles. Draw one. P(blue).

3/10

500

Form a 2-digit number from digits 1–5 without repetition (all equally likely). P(number is odd).

3/5

Measures of Central Tendency

100

Mean of 2, 4, 6, 8.

5

200

Median of 3, 7, 9, 2, 5.

5

300

Mode of 4, 4, 5, 6, 6, 6, 7.

6

400

Four numbers have mean 13. Three are 10, 12, 15. Find the fourth.

15

500

Data: 6, 8, 8, 9, 10, 12. Add 20. What is the new mean?

73/7 (≈10.43)

Interpreting Statistical Data

100

Which center is less affected by outliers: mean or median?

Median

200

Two classes have the same mean 75. Class A median 75; Class B median 68. Which likely has some very high scores?

Class B

300

If the median score is 12, what can you say about how many scores are at least 12?

At least half

400

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

500

Two stores have median weekly sales 100k. Store X mean=150k; Store Y mean=110k. Which likely has more extreme high days?

Store X