Answer:
He invest for 2 years.
Step-by-step explanation:
Given : Suppose you have $1,950 in your savings account at the end of a certain period of time. You invested $1,700 at a 6.88% simple annual interest rate.
To find : How long, in years, did you invest your money?
Solution :
Applying simple interest formula,
[tex]A=P(1+r)^t[/tex]
Where, A is the amount A=$1950
P is the principal P=$1700
r is the interest rate r=6.88%=0.0688
t is the time
Substitute the values in the formula,
[tex]1950=1700(1+0.0688)^t[/tex]
[tex]\frac{1950}{1700}=(1.0688)^t[/tex]
[tex]1.147=(1.0688)^t[/tex]
Taking log both side,
[tex]\log(1.147)=\log ((1.0688)^t)[/tex]
Applying logarithmic formula, [tex]\log a^x=x\log a[/tex]
[tex]\log(1.147)=t\log (1.0688)[/tex]
[tex]t=\frac{\log(1.147)}{\log (1.0688)}[/tex]
[tex]t=2.06[/tex]
Approximately, He invest for 2 years.