PLEASE HELP ASAP!!
A savings account starts with $420. After 6 years of continuously compounding at an interest rate, r, the account has a balance of $1,300. What is the interest rate percentage (do not type % it is already there)? Round answer to the nearest hundredth.

Respuesta :

Answer:

18.83% (nearest hundredth)

Step-by-step explanation:

Continuous Compounding Formula

[tex]\sf A=P(e)^{rt}[/tex]

where:

  • A = amount
  • P = principal (initial amount)
  • e = mathematical constant ≈ 2.7183
  • r = interest rate (in decimal form)
  • t = time in years

Given:

  • A = $1,300
  • P = $420
  • t = 6 years

Substituting given values into the formula:

[tex]\sf \implies 1300=420(e)^{6r}[/tex]

[tex]\sf \implies \dfrac{1300}{420}=e^{6r}[/tex]

[tex]\sf \implies e^{6r}=\dfrac{65}{21}[/tex]

Taking natural logs of both sides:

[tex]\sf \implies \ln e^{6r}=\ln \dfrac{65}{21}[/tex]

[tex]\sf \implies 6r\ln e=\ln \dfrac{65}{21}[/tex]

[tex]\sf \implies 6r(1)=\ln \dfrac{65}{21}[/tex]

[tex]\sf \implies 6r=\ln \dfrac{65}{21}[/tex]

[tex]\sf \implies r=\dfrac16 \ln \dfrac{65}{21}[/tex]

[tex]\sf \implies r=0.1883108054...[/tex]

Therefore, the interest rate is 18.83% (nearest hundredth)