Social Democrat Sanna Marin said on Tuesday she would restore stability to Finland and keep using social media - but with care - after being sworn in as the world's youngest prime minister at the helm of a government led by women.br br Marin, 34, won a confidence vote in parliament, with 99 in favour and 70 against, and will head a coalition government in which four of the five parties are led by women and 12 of the 19 members of the new cabinet are women.