Here are all the results with descriptions
keep your lips closely sealed
Do not, under any circumstances, tell this girl that you like her. She has given absolutely no signs that she will welcome your interest. If you can accept a no gracefully, ask. But if not, you need to get over those feelings and move on or wait until a better time.
get someone else to ask her
It's hard to resist the urge to blurt out your feelings, but you should not do it because you will scare her away. If you have to know, ask a trustworthy and reliable friend to ask some discreet questions to find out how she feels about you.
tell her hypothetically
It's not really safe to tell this girl how you feel because the signs just aren't clear about her feelings about you. If you tell her using a 'What would you say if I told you. . . ' scenario, at least she would get an idea how you feel and then she can gently encourage or discourage you.
ask her how she feels
From your description of the girl, she seems mature enough to handle a serious conversation. First, spell out how you feel and why. Then, respectfully ask her if she has feelings for you or if she'd be willing to go on a date.
tell her, but prepare for the worst
Prepare for the worst; hope for the best! Tell her how you feel. But, if she doesn't like you, don't throw a tantrum or say anything unkind. Simply, accept her answer and move on. But if she likes you. . . Well, we don't have to tell you what to do!
tell her right now
For your own peace of mind and heart, you are going to have to tell her how you feel you feel. From what you have shared, it seems like the response might be positive, but you will never know for sure unless you pour out your heart.