Questions: The money multiplier equals: reserve requirement/expenditure multipler. 1/marginal propensity to save. 1 / reserve requirement. marginal propensity to save/reserve requirement.

The answer is the third one: $1 /$ reserve requirement.

Explanation for each option:

1. Reserve requirement/expenditure multiplier: This is incorrect. The money multiplier is not calculated by dividing the reserve requirement by the expenditure multiplier. The expenditure multiplier is related to fiscal policy and not directly to the money supply process.

2. 1/marginal propensity to save: This is incorrect. The marginal propensity to save (MPS) is related to the expenditure multiplier in fiscal policy, not the money multiplier in monetary policy.

3. $1 /$ reserve requirement: This is correct. The money multiplier is calculated as the reciprocal of the reserve requirement ratio. It shows how much the money supply can increase based on an initial deposit, given the reserve requirement set by the central bank.

4. Marginal propensity to save/reserve requirement: This is incorrect. This formula does not relate to the calculation of the money multiplier.

In summary, the money multiplier is determined by the formula $1 /$ reserve requirement, which reflects how much the banking system can expand the money supply based on the reserves held.