2.1 Investment: The Demand for Loanable Funds Investment is still a downward-sloping function of the interest rate, but the exogenous world interest rate. 米 .determines the country's level of investment. I(r） I(r*) SI CHAPTER 8 The Open Economy slide 13CHAPTER 8 The Open Economy slide 13 Investment: The Demand for Loanable Funds Investment is still a downward-sloping function of the interest rate, r * but the exogenous world interest rate. .determines the country’s level of investment. I (r*) r S, I I (r ) 2.1