It sounds like it is an older mobile home with that interest rate. The $11K may be their up front points and fees which can run about 3% of the purchase. Don't take out a loan unless you fully understand the rate, terms and all fees associated with it.
Terri's spot on. What you're doing sounds like it's a desperate act to just get a roof over your head. Before you sign anything get some more answers and email me with the details. Or if you're comfortable comment about it on this thread. But something sounds pretty "TRAILER TRASHY".