The dot plots below show the ages of students belonging to two groups of music classes:

a dot plot shows two divisions labeled group a and group b. the horizontal axis is labeled as age of music students in years. group a shows 5 dots at 6, 5 dots at 8, 3 dots at 9, 7 dots at 11, and 5 dots at 13. group b shows 2 dots at 6, 4 dots at 10, 4 dots at 13, 3 dots at 15, 5 dots at 16, 4 dots at 19, and 3 dots at 21.

based on visual inspection, which group most likely has a lower mean age of music students? explain your answer using two or three sentences. make sure to use facts to support your answer.