Compound Interest and Financial Exponential Problems

The question involves compound interest or financial growth modelled by exponential expressions, asking the student to determine shares, totals, or time periods.

brazil-enem 2011 Q173 View
Um capital é aplicado a juros compostos de 10\% ao ano. Após 2 anos, o montante é R\$\,12\,100,00. O capital inicial é
(A) R\$\,9\,000,00 (B) R\$\,9\,500,00 (C) R\$\,10\,000,00 (D) R\$\,10\,500,00 (E) R\$\,11\,000,00
brazil-enem 2024 Q158 View
The compound interest on R\$\,1{,}000.00 at a rate of 10\% per year for 2 years is:
(A) R\$\,100.00
(B) R\$\,200.00
(C) R\$\,210.00
(D) R\$\,220.00
(E) R\$\,230.00