Answer:
20 days
Step-by-step explanation:
Number of books sold each day for 40 days :
The first quartile (Q1) = 2
For the 25% of the days = 2 books were sold
Hence 0.25 * 40 = 10 days, 2 books or less were sold
The upper quartile (Q3) = 12 books
For up to 75% of the days = 0.75 * 40 = 30 days ; 12 books or less were sold
To obtain the number of books sold between 2 and 12 ; we subtract :
(30 days - 10 days) = 20 days
