Which female challengers featured in episode 28?
CREATE TABLE "table1_24051050_1" (
  "episode" real,
  "contest" text,
  "original_airdate" text,
  "challengers_female" text,
  "challengers_male" text,
  "events" text
);
SELECT "challengers_female" FROM "table1_24051050_1" WHERE "episode"=28;