The following table gives the average balances for one bank customer for the months of July through September Average Monthly Balances for a Bank Customer $($July through September$)$ Month Average Balance $402\mathrm{.}45$ August $322\mathrm{.}97$ September $298\mathrm{.}64$ Calculate the average monthly balance for the three$-$month period of July through September Note that, since each month contains a different number of days, the average balance for each month must be weighted by the number of days in that month