Final answer:
The amount of consumption goods a young individual receives in middle-age for one good invested in money when young, in an economy without banks, depends on inflation and typically results in fewer goods due to the reduced purchasing power of money.
Step-by-step explanation:
In an economy without banks, if a young individual uses one consumption good to acquire money when young (at time t), the number of consumption goods they receive in middle age from the acquired money will depend on the rate at which the price level changes due to inflation (which is often tied to the growth rate of money supply).
If the money supply grows at a rate z, while the number of goods produced (y units of the consumption good) does not increase at the same rate, the individual will likely receive fewer consumption goods in exchange for the money because of the decreased purchasing power of money.
Assuming the price of the consumption goods increases at the same rate as the money supply, the individual would receive 1/z units of the consumption good in the next period.