CREATE TABLE table_28430 ("Specimen weight/size" CLOB, "Calculated activity  (  Bq  ) " FLOAT, "Calculated activity  (  Ci  ) " CLOB, "Estimated activity GR ( api ) " CLOB, "Estimated exposure  (  mRem  ) /hr*" CLOB)

if the estimated exposure ( mrem )/hr* is 0.28, what is the specimen weight/size?
SELECT COUNT("Specimen weight/size") FROM table_28430 WHERE "Estimated exposure ( mRem )/hr*" = '0.28'
SELECT COUNT("Specimen weight/size") FROM "table_28430" WHERE "Estimated exposure ( mRem )/hr*" = '0.28'