Answer:
a) Interest earned = $36
New Balance = $336
b) Interest rate = 0.05 or 5%
New Balance = $517.5
c) time t = 5
New Balance = $612.5
d) Principal Amount = $675
New Balance = $783
Step-by-step explanation:
We are given:
a) Principal (P) = $300
Rate (r) = 3% or 0.03
Time (t)= 4 years
Interest earned = ?
The formula used is: [tex]Simple \ Interest (I)= P\times r\times t[/tex]
Putting values and finding interest
[tex]Simple \ Interest (I)= P\times r\times t\\Simple \ Interest (I)= 300\times 0.03\times 4\\Simple \ Interest (I)= 36[/tex]
So, Interest earned = $36
New Balance = Principal + Interest = 300+36 = $336
b) a) Principal (P) = $300
Rate (r) = ?
Time (t)= 3 years
Interest earned = 67.50
The formula used is: [tex]Simple \ Interest (I)= P\times r\times t[/tex]
Putting values and finding rate
[tex]Simple \ Interest (I)= P\times r\times t\\67.50= 450\times r\times 3\\67.50=1350\times r\\r=\frac{67.50}{1350}\\r=0.05 \ or \ 5\%[/tex]
So, Interest rate = 0.05 or 5%
New Balance = Principal + Interest = 450+67.50 = $517.5
c) Principal (P) = $500
Rate (r) = 4.5% or 0.045
Time (t)= ?
Interest earned = $112.50
The formula used is: [tex]Simple \ Interest (I)= P\times r\times t[/tex]
Putting values and finding time
[tex]Simple \ Interest (I)= P\times r\times t\\112.50= 500\times 0.045\times t\\112.50=22.5 \times t\\t=\frac{112.50}{22.5}\\t=5[/tex]
So, time t = 5
New Balance = Principal + Interest = 500+112.50 = $612.5
d) Principal (P) = ?
Rate (r) = 8% or 0.08
Time (t)= 2 years
Interest earned = 108.00
The formula used is: [tex]Simple \ Interest (I)= P\times r\times t[/tex]
Putting values and finding Principal
[tex]Simple \ Interest (I)= P\times r\times t\\108=P\times 0.08 \times 2\\108=P\times 0.16\\P=\frac{108}{0.16}\\P=675[/tex]
So, Principal Amount = $675
New Balance = Principal + Interest = 675+108 = $783
