Respuesta :

first we need to put the numbers in order
4,4,9,9,18,18,20,20

minimum (lowest number) = 4
maximum (highest number) = 20
Q1 = (9 + 4)/2 = 13/2 = 6.5
Q2 (median) = (18 + 9)/2 = 27/2 = 13.5
Q3 = (18 + 20)/2 = 38/2 = 19