SQL Server 2019

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

create table ParticipantForm (AgeGroup varchar(100)
                              , Start_Nr int
                              , First_name varchar(100)
                              , Last_Name varchar(100)
                              , Distance_result float)
insert into ParticipantForm values('M30', 5, 'John', 'Lala', 180)
1 rows affected

insert into ParticipantForm values('M30', 3, 'Peter', 'Mikel', 190)
1 rows affected

insert into ParticipantForm values('M35', 1, 'Paul', 'Baba', 175)
1 rows affected

insert into ParticipantForm values('M35', 6, 'Patric', 'Ziza', 192)
1 rows affected

SELECT  [AgeGroup],
    [Start_Nr] ,
    [First_name],
    [Last_name],
    [Distance_result], 
    (select round(min(p2.Distance_result)/cast(p1.Distance_result as float) * 1000, 0) AS POints 
     from ParticipantForm p2
     where p2.AgeGroup = p1.AgeGroup
     group by p2.AgeGroup) as Points, 
DENSE_RANK() OVER (PARTITION BY [AgeGroup] ORDER BY [Distance_result] ASC) AS PlaceRank
FROM [ParticipantForm] p1


AgeGroup
Start_Nr
First_name
Last_name
Distance_result
Points
PlaceRank


M30
5
John
Lala
180
1000
1

M30
3
Peter
Mikel
190
947
2

M35
1
Paul
Baba
175
1000
1

M35
6
Patric
Ziza
192
911
2

AgeGroup	Start_Nr	First_name	Last_name	Distance_result	Points	PlaceRank
M30	5	John	Lala	180	1000	1
M30	3	Peter	Mikel	190	947	2
M35	1	Paul	Baba	175	1000	1
M35	6	Patric	Ziza	192	911	2