In Ruth 1:8-9 Naomi prays that her daughters-in-law will find husbands. She knows that they are both in difficult positions and she entrusts their situations to God. Of course, as the story continues we know Ruth doesn't abandon Naomi. Then, in Ruth 3:1 Naomi sets about securing a husband for Ruth. Not only is she looking for a husband for her daughter in law, she initiates a detailed plan in order to get one. She is answering her own prayer, yet nowhere in the book does this come across as a lack of faith, rather a response of faith. Naomi has seen a God given opportunity, and she is taking it. God has answered her prayer, but she needs to grasp it using all her wisdom.
Its an example of God's sovereignty and Naomi's cunning working together.