Question: What is the average age of all of the members of the club called "Bootup Baltimore"?
SQL: SELECT avg ( t3.age )  FROM club AS t1 JOIN member_of_club AS t2 ON t1.clubid   =   t2.clubid JOIN student AS t3 ON t2.stuid   =   t3.stuid WHERE t1.clubname   =   "Bootup Baltimore"