Start building the two-way frequency table: it will have three rows (cat, no cat, total) and three columns (dog, no dog, total).
Start filling the table with the data you know:
| dog | no dog | total
cat | | | 17 |
no cat | | 7 | |
total | | 20 | 41 |
Now you can make easy calculations in order to fill the blanks:
- the number of patrons with cats but not dogs: (20 - 7) = 13;
- the number of total dogs: (41 - 20) = 21
- the total number of patrons with no cats: (41 - 17) = 24.
Now the table looks like this:
| dog | no dog | total
cat | | 13 | 17 |
no cat | | 7 | 24 |
total | 21 | 20 | 41 |
And you can use the new data to complete the table:
- the number of patrons with cats and dogs: (17 - 13) = 4
- the number of patrons with dogs and no cats: (24 - 7) = 17
The final table is in the picture attached.
