Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE Lives_in ( stuid INTEGER, dormid INTEGER, room_number INTEGER )
TABLE: CREATE TABLE Has_amenity ( dormid INTEGER, amenid INTEGER )
TABLE: CREATE TABLE Student ( StuID INTEGER, LName VARCHAR(12), Fname VARCHAR(12), Age INTEGER, Sex VARCHAR(1), Major INTEGER, Advisor INTEGER, city_code VARCHAR(3) )
TABLE: CREATE TABLE Dorm_amenity ( amenid INTEGER, amenity_name VARCHAR(25) )
TABLE: CREATE TABLE Dorm ( dormid INTEGER, dorm_name VARCHAR(20), student_capacity INTEGER, gender VARCHAR(1) )

### Question ###
Find the number of students whose age is younger than the average age and group by students' first name in a bar chart, could you show in descending by the y axis?

### Accurate SQL ###

SELECT Fname, COUNT(Fname) FROM Student WHERE Age < (SELECT AVG(Age) FROM Student) GROUP BY Fname ORDER BY COUNT(Fname) DESC