The box plots below show the average gas mileage, in miles per gallon, of the cars sold at a dealership in June and in December. Gas Mileage of Cars Sold in June
2 box plots. The number line goes from 14 to 34. For cars sold in June, the whiskers range from 21 to 33, and the box ranges from 22 to 29. A line divides the box at 24. For Cars sold in December, the whiskers range from 14 to 26, and the box ranges from 18 to 21. A line divides the box at 19.
Gas Mileage of Cars Sold in December

The manager used the table below to compare the measures of center and the measures of variability.

Median
Range
Interquartile Range
Sold in June
24
33 minus 21 = 12
29 minus 22 = 7
Sold in December
19
26 minus 14 = 12
21 minus 16 = 5

What error did the manager make in the table?