which of the following is not correct? a. the equilibrium real interest rate is 6 percent, and the equilibrium quantity of loanable funds is $1.6 trillion. b. at an interest rate of 8 percent, there is a surplus of loanable funds. c. at an interest rate of 4 percent, there is a shortage of loanable funds. d. at an interest rate of 4 percent, the quantity supplied of loanable funds equals $18 trillion.