Applications of Indices Surds and Logarithms

Question

Ahmad deposited RM3 500 in a fixed deposit account with the interest rate of 5% per annual and compounded yearly. Determine the number of years taken for his account to become RM 5 431.20.

Answer 1

An alternate to William W.'s ending

1.55177 = 1.05^t

ln 1.55177 = t ln 1.05

0.439396214 ≈ 0.048790164 t

9.00583594 ≈ t

Answer 2

5431.20 = 3500(1.05)^t

5431.20/3500 = 1.05^t

1.55177 = 1.05^t

Converting an exponential equation into a logarithmic equation:

log_1.05(1.55177) = t and then plugging this into a calculator, we get:

t = 9.0058548 or

t = 9 years