Then he uses the outcomes from the table to include the third spinner.
W
X
Y
Z
AL
ALW
ALX
ALY
ALZ
AM
AMW
AMX
AMY
AMZ
AN
ANW
ANX
ANY
ANZ
BL
BLW
BLX
BLY
BLZ
BM
BMW
BMX
BMY
BMX
BN
BNW
BNX
BNY
BNZ
Lin creates a tree to keep track of the outcomes.
How many outcomes are in the sample space for this experiment?
One of the outcomes from Diego’s list is BLX. Where does this show up in Tyler's method? Where is it in Lin’s method?
When spinning all three spinners, what is the probability that:
They point to the letters ANY? Explain your reasoning.
They point to the letters AMW, ANZ, or BNW? Explain your reasoning.
If a fourth spinner that has 2 equal sections labeled S and T is added, how would each of the methods need to adjust?
3.3
Activity
Sample Space Practice
List all the possible outcomes for each experiment.
A standard number cube is rolled, and then a coin is flipped.
Four coins are flipped.
The two spinners are spun.
A class block is chosen from 1, 2, 3, 4, or 5, and then a subject is chosen from English or math.
Student Lesson Summary
Probability represents the proportion of the time an event will occur when repeating an experiment many, many times. For complex experiments, the sample space can get very large very quickly, so it is helpful to have some methods for keeping track of the outcomes in the sample space.
In some cases, it makes sense to list all the outcomes in the sample space. For example, when flipping 3 coins, the 8 outcomes in the sample space are:
HHH, HHT, HTH, THH, HTT, THT, TTH, TTT, where H represents heads and T represents tails.
With more outcomes possible, it can be difficult to make sure all the outcomes are represented and none are repeated, so other methods may be helpful.
Another option is to use tables. When a complex experiment is broken down into parts, tables can be used to find the outcomes of two parts at a time.
For example, when flipping 3 coins, we determine the outcomes for flipping just 2 coins. The possible outcomes are represented by the 4 options in the middle of the table: HH, HT, TH, and TT.
These outcomes can then be combined with the third coin flip in another table. Again, we see that the outcomes are HHH, HHT, HTH, HTT, THH, THT, TTH, and TTT.
H
T
H
HH
HT
T
TH
TT
H
T
HH
HHH
HHT
HT
HTH
HTT
TH
THH
THT
TT
TTH
TTT
Another way to keep track of the outcomes is to draw a tree structure. Each column represents another part of an experiment, with branches connecting each possible result from one part of the experiment to the possible results for the next part. By following the branches from left to right, each path represents an outcome for the sample space. The tree for flipping 3 coins would look like this. The path shown with the dashed line represents the HTH outcome. By following the other paths, the other 7 outcomes can be seen.
Tree diagram. On top, H with 2 branches, labeled H and T. From H, two branches labeled H and T. From T, two branches labeled H and T. Dashed line from H to T, and T to H. Below, T with 2 branches labeled H and T. From H, two branches labeled H and T. From T, two branches labeled H and T.