Question

Calcule o valor dos juros que um cliente pagará ao efetuar um pagamento de uma parcela no valor de R$ 300,00 com 12 dias de atraso com uma multa de 2% de juros ao dia.

Answer 1

No Regime de Juros Simples, fica:

$Juros~=~Capital\times Taxa\times Periodo\\\\\\Juros~=~300\times \frac{2}{100}\times 12\\\\\\Juros~=~\frac{300~.~2~.~12}{100}\\\\\\Juros~=~\frac{3~.~2~.~12}{1}\\\\\\\boxed{Juros~=~72~reais}$

No Regime de Juros Compostos, fica:

$Montante~=~Capital\times(1+Taxa)^{periodo}\\\\\\Capital+Juros~=~Capital\times(1+Taxa)^{periodo}\\\\\\Juros~=~Capital\times(1+Taxa)^{periodo}-Capital\\\\\\Juros~=~300\times\left(1+\frac{2}{100}\right)^{12}-300\\\\\\Juros~=~300\times\left(1,02\right)^{12}-300\\\\\\Juros~=~300\times 1,2682-300\\\\\\Juros~=~380,46-300\\\\\\\boxed{Juros~=~80,46~reais}$