Answer:
The amount they initially invest in 1991 is;
Step-by-step explanation:
Given the expression;
Where;
F= final amount
p=initial investment
r= annual interest rate
t=time in years
Given that;
The amount in the account in 1996 is $4,000, annual interest rate at 3% ;
Making p the subject of formula;
substituting the values;
Therefore, the amount they initially invest in 1991 is;