The given preferred stock is cumulative and hence any unpaid dividend shall be cumulated and paid in next year.
The Annual preferred dividend is calculated as follows:
2100 shares * $10 par value * 6.5%= $1,365
In the first year, the dividend paid to preferred stock is $1,000, it means unpaid dividend is (1365-1000) = 365, which shall be paid in the second year.
Hence in the second year total dividend payable to preferred shall be $1365+ 365 = $1,730
Hence, the cash dividend that must be paid to preferred stockholders in the second year before any dividend is paid to common stockholders is $1,730