Exercise 1. Decide if the following variables are qualitative or quantitative, and in the latter case if continuous or discrete:

1. a) number of inhabitants/square km
2. b) types of products alimentation canned
3. c) number of bacteria type A/liter
4. d) density of different liquids
5. e) number of fruits/tree
6. f) speed of a vehicle at a certain point of the motorway
7. g) number of children a family has
8. h) exam grade in %
9. i) unemployment benefit obtained
10. j) weight of one year old babies
11. k) how many books one has at home
12. l) genre of the book you are reading
13. m) number of letters a book has
14. n) distance between Barcelona and the hometown of somebody

Exercise 2. We have asked some students, how many subjects they take this semester, and got the following ansers: 1, 6, 7, 3, 8, 5, 4, 3, 2, 1, 6, 8, 7, 4, 5, 7, 5, 8, 4, 3, 5. Determine the frequency table. Read the % of the students having at most 5 classes, more than 6 classes and exactly 7 classes.

Exercise 3. Number or hours people normally sleep: 6.5, 3.4, 8.5, 4.2, 5.9, 6.4, 7.6, 9.2, 10.1, 5.5, 6.4, 8.3, 7.4, 7.6, 5.2, 4.3, 6.4, 3.6. Determine the frequency table of the scores, using classes of 0-4 hours, 4-6, 6-8, 8+ hours.