The ages of two groups of dance students are shown in the following dot plots:  A dot plot shows Age in years on the horizontal axis. 
For Group X, there are 3 dots on 4, 1 dot on 5, 5 dots on 8, 2 dots on 10, 3 dots on 12, and 2 dots on 16. 
For Group Y, there are 2 dot on 5, 3 dots on 7, 1 dot on 9, 3 dots on 11, 1 dot on 13, 2 dots on 14, 1 dot on 15, 1 dot on 18, 3 dots on 20, 1 dot on 22, and 2 dots on 24.  
The mean absolute deviation (MAD) for group X is 3.07 and the MAD for group Y is 5.25. 
Which of the following observations can be made using these data?  
 Group X has less variability in the data.  
Group X has greater variability in the data.  
Group Y has a lower range.  
Group Y has a lower mean.