The two dot plots below show the heights of some sixth graders and some seventh graders:
Two dot plots are shown one below the other. The title for the top dot plot is Sixth Graders and the title for the bottom plot is Seventh Graders. Below the line for each dot plot is written Height followed by inches in parentheses. There are markings from 52 to 57 on the top line and the bottom line at intervals of one. For the top line there are 2 dots above the first mark, 1 dot above the second mark, 1 dot above the third mark and 2 dots above the fourth mark. For the bottom line, there is 1 dot for the first mark, there is 1 dot above the second mark, there is 1 dot above the third mark, there is 1 dot above the fourth mark and there are two dots above the sixth mark.

The mean absolute deviation (MAD) for the first set of data is 1.2 and the MAD for the second set of data is 1.7. Approximately how many times the variability in the heights of the sixth graders is the variability in the heights of the seventh graders? (Round all values to the tenths place.)

1.2
1.4
2.4
2.8