Respuesta :
Answer:
the annual interest rate is 0.67%
Explanation:Amount invested = $8000
Future value = $8400
time = 7 1/2 yeras
rate = ?
To answer the question, we will apply the simple interset formula:
[tex]\begin{gathered} I\text{ = P}\times R\times T \\ P\text{ = principal = 8000} \\ R\text{ = ?} \\ T\text{ = time = 7}\frac{1}{2} \\ I\text{ = interest = ?} \end{gathered}[/tex][tex]\begin{gathered} Future\text{ value = Principal + interest} \\ 8400\text{ = 8000 + interest} \\ Interest\text{ = 8400 - 8000} \\ Interest\text{ = 400} \end{gathered}[/tex]substitute the values into the simple interest formula to get r:
[tex]\begin{gathered} 400\text{ = 8000}\times r\times7\frac{1}{2} \\ 400\text{ = 8000}\times r\times\frac{15}{2} \\ 400\text{ = 60000r} \\ r\text{ = 400/60000} \\ r\text{ = 0.0067} \end{gathered}[/tex]In percentage, the annual interest rate is 0.67%
