What are the average, minimum, and max ages for each of the different majors?
return different majors ;return ages of  #1 ;return average of  #2 for each  #1 ;return minimum of  #2 for each  #1 ;return max of  #2 for each  #1 ;return #3 ,  #4 ,   #5
['select', 'project', 'group', 'group', 'group', 'union']