initialvalue = 1000
m1start = 100
m2start = 100
m3start = 100
v3end = 1500

=RATE(3,-100,-1000,1500,1)

0.0528704

v3end = (100 (1 + r) ((1 + r)^3 - 1))/r + initialvalue (1 + r)^3

initialvalue = 1000
m1start = 100
v1end = 1158
m2start = 100
v2end = 1325
m3start = 100
v3end = 1500


(1158/(1000 + 100)*1325/(1158 + 100)*1500/(1325 + 100))^(1/3) - 1 = 0.0528726

initialvalue = 1000
m1start = 100
v1end = 1150
m2start = 80
v2end = 1250
m3start = 120
v3end = 1500

(1150/(1000 + 100)*1250/(1150 + 80)*1500/(1250 + 120))^(1/3) - 1 = 0.0517041