Open the Fair Coins Starter File, which defines coin1, coin2, and coin3. Click "Run".
You can flip each coin by evaluating flip(coin1) in the Interactions Area (repeat for coins 2 and 3).
One of these coins is fair, one will land on "heads" 75% of the time, and one will land on "heads" 90% of the time. *Which one is which?*
Answers are not provided because they will be different for each student!
1 Complete the table below by recording the results for five flips of each coin and totalling the number of "heads" you saw.
Convert the ratio of heads to flips into a percentage. Finally, decide whether or not you think each coin is fair based on your sample.
| Sample | coin1 | coin2 | coin3 | |||
|---|---|---|---|---|---|---|
1 |
H |
T |
H |
T |
H |
T |
2 |
H |
T |
H |
T |
H |
T |
3 |
H |
T |
H |
T |
H |
T |
4 |
H |
T |
H |
T |
H |
T |
5 |
H |
T |
H |
T |
H |
T |
#heads |
/5 |
/5 |
/5 |
|||
% heads |
% |
% |
% |
|||
fair? |
Y |
N |
Y |
N |
Y |
N |
2 Record 15 more flips of each coin in the table below and total the number of "heads" you saw in all 20 flips of each coin.
Convert the ratio of total heads to total flips into a percentage. Finally, decide whether you think each coin is fair based on this larger sample.
| Sample | coin1 | coin2 | coin3 | |||
|---|---|---|---|---|---|---|
6 |
H |
T |
H |
T |
H |
T |
7 |
H |
T |
H |
T |
H |
T |
8 |
H |
T |
H |
T |
H |
T |
9 |
H |
T |
H |
T |
H |
T |
10 |
H |
T |
H |
T |
H |
T |
11 |
H |
T |
H |
T |
H |
T |
12 |
H |
T |
H |
T |
H |
T |
13 |
H |
T |
H |
T |
H |
T |
14 |
H |
T |
H |
T |
H |
T |
15 |
H |
T |
H |
T |
H |
T |
16 |
H |
T |
H |
T |
H |
T |
17 |
H |
T |
H |
T |
H |
T |
18 |
H |
T |
H |
T |
H |
T |
19 |
H |
T |
H |
T |
H |
T |
20 |
H |
T |
H |
T |
H |
T |
#heads |
/20 |
/20 |
/20 |
|||
% heads |
% |
% |
% |
|||
fair? |
Y |
N |
Y |
N |
Y |
N |
3 Which coin was the easiest to identify? fair? 75%? 90%?
4 Why was that coin the easiest to identify?
These materials were developed partly through support of the National Science Foundation, (awards 1042210, 1535276, 1648684, 1738598, 2031479, and 1501927). 
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