คู่ไหนมีค่าเฉลี่ย 17.2?ไม่จำเป็นต้องใช้ทุกโต๊ะ
What couple has an average of 17.2?It is not neccessary to use all the tables.
 table_20424140_3:  (couple [ VARCHAR ] average [ VARCHAR) ]
SELECT couple FROM table_20424140_3 WHERE average = "17.2"