The following box-and-whisker plot shows the number of text messages sent by students in a school on a particular day.
Find the value of the interquartile range.
One student sent k text messages, where k > 11 . Given that k is an outlier, find the least value of k.
recognizing Q1 or Q3 (seen anywhere) (M1)
eg 4,11 , indicated on diagram
IQR = 7 A1 N2
recognizing the need to find 1.5 IQR (M1)
eg 1.5 × IQR, 1.5 × 7
valid approach to find k (M1)
eg 10.5 + 11, 1.5 × IQR + Q3
k = 22 A1 N3
Note: If no working shown, award N2 for an answer of 21.5.