# ✅ Quiz M1.03
```{admonition} Question
How are categorical variables represented?
- a) categorical feature is only represented by non-numerical data
- b) categorical feature represents a finite number of values called categories
- c) categorical feature can either be represented by numerical or non-numerical values
_Select all answers that apply_
```
+++
```{admonition} Question
An ordinal variable:
- a) is a categorical variable with a large number of different categories;
- b) can be represented by integers or string labels;
- c) is a categorical variable with a meaningful order.
_Select all answers that apply_
```
+++
```{admonition} Question
One-hot encoding:
- a) encodes each column with string-labeled values into a single integer-coded column
- b) transforms a numerical variable into a categorical variable
- c) creates one additional column for each possible category
- d) transforms string-labeled variables using a numerical representation
_Select all answers that apply_
```
+++
```{admonition} Question
Assume we have a dataset where each line describes a company. Which of the
following columns should be considered as a meaningful **numerical feature** to
train a machine learning model to classify companies:
- a) the sector of activity ("construction", "retail", "energy", "insurance"...)
- b) the phone number of the sales department
- c) the number of employees
- d) the profits of the last quarter
- e) the post code of the head quarters
_Select all answers that apply_
```