Since the preferred stocks are cumulative in nature, the dividend amount not paid in the current year will be accumulated and paid in the next year.
Preferred dividend to be paid in 2017 = Value of preferred stock x Dividend rate
= (4700 x $50) x 5%
= 11750
Dividend to be paid in 2018 = same as 2017 as no new preferred stock issued
= 11750
Total dividend to be paid in 2018 = Dividend to be paid in 2018 + Dividend to be paid in 2017 – Dividend paid in 2017
= 11750 +11750 -7900
= $15600