Resposta:=0,858789297% ou 0,86%
Explicação passo-a-passo:
C=25000,Mc=27000,n=9 meses,i=?
Mc=C.(1+i)^n
27000=25000.(1+i)^9
27000/25000=(1+i)^9
1,08=(1+i)^9
(1+i)^9=1,08
1+i=9^√1,08
1+i=1,00858789297
i=1,00858789297-1
i=0,00858789297 x 100
i=0,858789297% ou 0,86%