Simple Interest
Given a situation where an investment of P dollars is made at a rate r for t years, the interest earned is given by:
I = P.r.t
The final value (FV) is the sum of the principal p and the interest earned:
FV = P + P.r.t
Factoring P:
FV = P (1 + r.t)
This equation allows calculating the final value when we know P, r, and t. If we need to know the value of t, we solve the previous equation for t:
FV = P (1 + r.t)
Dividing by P:
1 + r.t = FV/P
Subtracting 1:
r.t = FV/P - 1
Dividing by r:
The data provided in the question is p=$2250, FV=$5000, r=6.2%.
Converting to decimal: r=0.062. Substituting:
The time required is approximately 20 years (rounding up)