Eight car dealerships reported the number of cars they sold last month. car dealership number of cars sold gmc 84 chevrolet 81 nissan 92 toyota 92 ford 95 honda 94 hyundai 80 acura 72 what is the interquartile range of this set of data?

The interquartile range is 12.5.

We first find the median.  To do this, order the data from least to greatest and find the middle value:
72, 80, 81, 84, 92, 92, 94, 95

There are 8 data values.  The median is between 84 and 92:
(84+92)/2 = 176/2 = 88

The median splits the data into two halves.  The lower quartile is the median of the lower half; this is between 80 and 81:
(80+81)/2 = 161/2 = 80.5

The upper quartile is the median of the upper half; this is between 92 and 94:
(92+94)/2 = 186/2 = 93

The interquartile range is found by subtracting these:
93-80.5 = 12.5

J= r + 9 because since jessica rode 9 more miles than roger, you add 9 miles to rogers mileage.