Remember that the formula for simple interest is:
[tex]I=Prt[/tex]
Where:
• I = Interest
,
• P = Initial value
,
• r = Interest rate
,
• t = time (years)
Let's use this and the data from the problems to calculate what's asked:
Problem #1
a)
[tex]\begin{gathered} I=(2500)(\frac{1.2}{100})(30) \\ I=900 \end{gathered}[/tex]
The costumer would earn $900 in interest.
b)
[tex]2500+900=3400[/tex]
The account balance be after 30 years would be $3400
Problem #2
After 4 years, the value of the account would be
[tex]\begin{gathered} 500+(500)(\frac{3.2}{100})(4) \\ \rightarrow564 \end{gathered}[/tex]
For the number line, put 4 in years and 64 in interest
Problem #3
Let's calculate the interest earned in 1 year for each one (M is Monica and P is Paul):
[tex]\begin{gathered} M=400(\frac{3.6}{100})(1)\rightarrow M=14.4 \\ P=500(\frac{3.1}{100})(1)\rightarrow P=15.5 \end{gathered}[/tex]
Monica is wrong.