Question: how much money was requested on the show which aired on 4 September 2011?
SQL: SELECT SUM("Money requested (£)") FROM "2-12617978-13" WHERE "First aired" = '4 September 2011';

Question: what investing dragons aired on Episode 10?
SQL: SELECT "Investing Dragon(s)" FROM "2-12617978-13" WHERE "Episode" = 'Episode 10';