Answer:
$3250
Step-by-step explanation:
The formula for simple interest is:
[tex]i=Prt[/tex]
Where
i is the simple interest earned
P is the principal (initial amount) invested
r is the rate of interest (in decimal)
t is the time in years
Given, 1.25% simple interest, in decimal, that is:
1.25/100 = 0.0125
r = 0.0125
and
i = 812.50
t = 20
Substituting, we find P:
[tex]i=Prt\\812.50=P(0.0125)(20)\\812.50=P(0.25)\\P=\frac{812.50}{0.25}\\P=3250[/tex]
The principal he invested was $3250
