ok...a starter to build upon

maybe this is what you require or maybe not.

please note......it would be helpful to post set up scripts and expected answers when you start a new question.

Also....you may well find that you over simplified your example....questions were asked before about start/end dates remaining constant per claim....i dont see this has been answered

USE tempdb

GO

CREATE TABLE yourtable(

insurer VARCHAR(4) NOT NULL

,claim_number INTEGER NOT NULL

,location VARCHAR(5) NOT NULL

,start_date DATETIME NOT NULL

,end_date DATETIME NOT NULL

);

INSERT INTO yourtable(insurer,claim_number,location,start_date,end_date) VALUES ('john',5555,'east','1/5/10','1/17/10');

INSERT INTO yourtable(insurer,claim_number,location,start_date,end_date) VALUES ('john',5555,'west','1/5/10','1/17/10');

INSERT INTO yourtable(insurer,claim_number,location,start_date,end_date) VALUES ('john',5555,'south','1/5/10','1/17/10');

INSERT INTO yourtable(insurer,claim_number,location,start_date,end_date) VALUES ('jane',3333,'west','4/6/12','4/16/12');

INSERT INTO yourtable(insurer,claim_number,location,start_date,end_date) VALUES ('jane',3333,'north','4/6/12','4/16/12');

INSERT INTO yourtable(insurer,claim_number,location,start_date,end_date) VALUES ('jane',3333,'east','4/6/12','4/16/12');

SELECT insurer

, claim_number

, cast(DATEDIFF(day, start_date, end_date) * 1.0 / COUNT(*) as decimal(9,2)) AS result

FROM yourtable

GROUP BY insurer

, claim_number

, start_date

, end_date