Tripling Money at Nominal Interest Rate

Question

Not sure what this questions means by "part of a year"? What assumptions should be made?

Question: How long will it take to triple your money at a nominal interest rate j1 = 12% if simple interest is allowed for part of a year?

Can anyone help?

Answer 1

Let $P$ be your money: $$P(1+jt)=3P\qquad\Longrightarrow\qquad 1+jt=3\qquad\Longrightarrow\qquad t=\frac{2}{12\%}=16.\bar6\,\text{years}$$ that is $16$ years and the fractional part $\frac{2}{3}=0.\bar6$ year (i.e. 8 months)