You can have 3 btc for a two weeks at 10% interest or one month at 20% interest. Meaning if you keep it for two weeks you must pay 3.3 btc or if you keep it for a month you must pay 3.6BTC back. I can go up to 5 btc loan, but the higher the loan the lower the interest rate. My rates:

Bitcoins: two weeks interest, one month interest
3btc: 10%, 20%
4btc: 8%,16%
5btc: 6%,12%

Kind regards,
Marty Lee