Given the set of data 4,17,7,14,18,12,3,16,10,4,4,11
in ascending order = 3,4,4,4,7,10,11,12,14,16,17,18
smallest value = 3
largest value = 18
Q1 = 1/4 x 12 = 3rd + 4th position = (4 + 4)/2 = 4
Q2 = median = 1/2 x 12 = 6th + 7th position = (10 + 11)/2 = 10.5
Q3 = 3/4 x 12 = 9th + 10th position = (14 + 16)/2 = 15
Then plot on a box and whisker those values using a suitable scale