CREATE TABLE table_6402 ("Result" CLOB, "Date" CLOB, "Race" CLOB, "Venue" CLOB, "Group" CLOB, "Distance" CLOB, "Weight  ( kg ) " FLOAT, "Time" CLOB, "Jockey" CLOB, "Winner/2nd" CLOB)

What was the combined weight in kilograms of the horses in the race at Chelmsford stakes?
SELECT COUNT("Weight (kg)") FROM table_6402 WHERE "Race" = 'chelmsford stakes'
SELECT COUNT("Weight (kg)") FROM "table_6402" WHERE "Race" = 'chelmsford stakes'