Not Financial Advice:
If you took out a loan for $4,000 that lasted for 3 years and had a 10% interest rate, your monthly payments would be $129.07.
At the end of those 3 years you will have paid $646.47 in interest, making the total that you repaid $4,646.47 for the original $4,000 you got.
These days, 10% would be a very high interest rate. In Pennsylvania, for example, in order to spur job growth the Department of Community and Economic Development has lowered rates on several of its loan programs from 2.75% to 1.5%.