Aviolin student records the number of hours she spends practicing during each of nine consecutive weeks. 6.2 5.0 4.3 7.4 5.8 7.2 8.4 1.2 6.3 what is the interquartile range (iqr) for this data?

We need to put the data set in ascending order

1.2     4.3     5.0     5.8     6.2     6.3     7.2      7.4     8.4

Interquartile range is given by upper quartile - lower quartile

Location of lower quartile = 1/4 of the data set
Location of upper quartile = 3/4 of the data set

Lower quartile = 1/4 of 9 = 2.25th (rounded down to 2nd  value) = 4.3
Upper quartile = 3/4 of 9 = 6.75th (rounded up to 7th value) = 7.2

Interquartile value = 7.2 - 4.3 = 2.9