Dear Innocent. I have more than 30 years working at a central bank. Thus, I would advise to reformulate your question and be more specific with respect to the 'cash reserve ratio' - 'monetary policy rate' relationship. It is quite possible that we need a third variable to understand clearly what is the point.

The cash reserve ratio (CRR) is based on the theory that by mandating banks to hold a certain percentage of their deposits in reserve, central banks can control the amount of money circulating in the economy. This regulation influences banks' lending capacity and helps manage inflation and stabilize the economy.

The monetary policy rate, such as the central bank's benchmark interest rate, is based on theories of influencing borrowing, spending, and investment behaviors. By adjusting this rate, central banks seek to regulate economic activity, such as inflation and economic growth, by influencing the cost of borrowing and the return on savings and investments.