Which of the following statements about exchange rate theories are correct?

1. The Purchasing Power Parity (PPP) theory suggests that exchange rates should equalize the price of identical goods in different countries.
2. The Interest Rate Parity (IRP) states that differences in interest rates between countries should be reflected in the forward exchange rates.
3. The Balassa-Samuelson effect explains how productivity differences affect exchange rates and the real exchange rate over time.
4. Floating exchange rates are determined solely by government intervention.