(1) Classical real interest rate theory: it is believed that interest rate is determined by practical factors such as investment and savings, and investment is the demand for funds, which decreases with the increase of interest rate; Savings is the supply of funds, which increases with the increase of interest rate. When the capital demand equals the capital supply, the equilibrium price is determined.

② liquidity preference interest rate theory: Keynes's interest rate determination theory from the perspective of money. It is believed that money demand mainly includes transactional demand, preventive demand and speculative demand. Money supply is an exogenous variable, which is mainly determined by monetary policy. The demand for funds is equal to the price when the funds are supplied.

③ loanable funds Theory: Considering both the product market and the money market, it is considered that the demand and supply of loan funds include two aspects. The demand for loan funds comes from the investment flow and monetary balance that people want to hold in a certain period of time; The supply of loan funds comes from the change of savings flow and money supply in the same period. Among them, money supply is positively correlated with interest rate, and money demand is negatively correlated with interest rate. Generally speaking, the equilibrium condition is: I+△ MD = S+△ Ms, so the supply and demand in loanable funds determine the equilibrium interest rate.

① IS-LM theory: The equilibrium interest rate is determined by income and interest rate. (See short answer 1)

(2) The relationship between monetary growth and interest rate level.

(1) In the short term, the increase of money supply will lead to an oversupply of funds in the money market, so the interest rate as the price of funds will inevitably fall, thus stimulating investment and consumption.

(2) In the long run, the increase of money supply will stimulate investment and consumption, thus increasing economic growth and total demand, and the demand for money in economy and society will also increase accordingly, leading to an increase in interest rates; At the same time, the rise of the price level will also push up the nominal interest rate. However, according to the "currency neutrality" of monetarism, the increase of money supply can only change the nominal interest rate in the long run, while the real interest rate remains unchanged.