Z = K * p/100 / 2 | wegen des halben Jahres
I. 140 = K * p/100 / 2 | 280 = K * p/100 | 280/K = p/100 | 28000/K = p
II. 160 = (K + 500) * p/100 / 2 | 320 = (K + 500) * p/100 | 32000 = (K + 500) * p | 32000/(K + 500) = p
I. = II.
28000/K = 32000/(K + 500) | Umkehrbruch
K/28000 = (K + 500)/32000 | * 32000
K * 32000 / 28000 = K + 500 | * 28000
K * 32000 = K * 28000 + 14000000
4000 * K = 14000000
K = 3500
In I.
28000/3500 = 8 = p
Zinssatz 8%
Kapital 3500 DM
Besten Gruß