engineering economics

Question

At what rate of annual interest will an investment quadruple itself in 12years

Answer 1

We want (1+i)¹²=4 that is, 1 dollar compounding annually at i will equal $4 in 12 years.

take the 12th root of both sides and get ((1+i)¹²)^(1/12)=1=i = 4^(1/12)

or i = 4^(1/12)-1 = 12.246%. as a check= (1+12.246%)¹² so, 1.12246¹² =3.99991 (rounding error) If you need help here please reach out