Answer: Account B had the greater principal because $400 is greater than $300
Explanation:
The formula for simple interest is expressed as
I = PRT/100
Where
P represents the principal
R represents interest rate
T represents time
Considering the investment in account A,
I = $15.75
R = 3%
T = 21 months = 21/12 = 1.75 years.
15.75 = (P × 3 × 1.75)/100 = 0.0525P
P = 15.75/0.0525 = $300
Considering the investment in account B,
I = $28
R = 4%
T = 21 months = 21/12 = 1.75 years.
28 = (P × 4 × 1.75)/100 = 0.07P
P = 28/0.07 = $400