Answer:
Step-by-step explanation:
The formula for simple interest is expressed as
I = PRT/100
Where
P = principal
T = time in years
R = interest rate on the principal.
For account A, the simple interest earned after 21 months is $13.65. The interest rate is 3.9% for Account A
Let y represent the principal for account B. Therefore
P = x
I = $13.65
T = 21/12 = 1.75 years
R = 3.9
Therefore
13.65 = (x × 3.9 × 1.75)/100
1365 = 6.825x
x = 1365/6.825 = $200
For account B, the simple interest earned after 30 months is $40.25. The interest rate is 2.3% for Account B
Let x represent the principal for account A. Therefore
P = y
I = $40.25
T = 30/12 = 2.5 years
R = 2.3
Therefore
40.25 = (y × 2.3 × 2.5)/100
4025 = 5.75y
y = 4025/5.75 = $700
The principal for account A is $200
The principal for account B is $700
For account A, interest earned in the first month is
13.65/21 = $0.65
For account B, interest earned in the first month is
40.25/30= $1.34
Account B earned the most interest in the first month(the same interest is earned every month)
