3.- A Tourism Office is going to conduct a survey on the number of sunny and rainy days that occur in a year. For this purpose, it turns to six regions that provide the following data:

| Region | Sunny or Rainy | Unclassifiable |
| :---: | :---: | :---: |
| A | 336 | 29 |
| B | 321 | 44 |
| C | 335 | 30 |
| D | 343 | 22 |
| E | 329 | 36 |
| F | 330 | 35 |

The person in charge of the survey is not impartial and has these data in more detail. They notice that, by excluding one of the regions, the observation gives a number of rainy days that is one-third of the number of sunny days. Reason which region they will exclude.
## Solution

By suppressing a region, the sum of sunny or rainy days of the remaining ones must be a multiple of 4. This sum, for the six regions, is 1994, which when divided by 4 leaves a remainder of 2. The only data in this column that gives a remainder of 2 when divided by 4 is 330, corresponding to region F. By removing this region, there remain 416 rainy days and 3$\cdot$416 $=1248$ sunny days among the five remaining regions.