7500 dollars is placed in an account with an annual interest rate of 5.25%. To the nearest tenth of a year, how long will it take for the account value to reach 25200 dollars?

Respuesta :

Answer:

After [tex]23.7\ years[/tex] the amount [tex]7500\ dollars[/tex] will reach to [tex]25200\ dollars[/tex].

Step-by-step explanation:

Given that,

                  Principle Amount [tex](P)[/tex] [tex]=7500\ dollars[/tex]

                  Rate of Interest [tex](R)[/tex] [tex]=5.25[/tex] %

                  Total Amount [tex](A)[/tex] [tex]= 25200\ dollars[/tex]

Now,

        If Principle [tex]=P[/tex] [tex]dollars[/tex], Time [tex]= t[/tex] years, Rate [tex]=R[/tex]% [tex]pa[/tex]

then, Amount after [tex]t[/tex] years [tex]=A=P(1+\frac{R}{100}) ^{t}[/tex]

⇒ [tex]A=P(1+\frac{R}{100}) ^{2}[/tex]

⇒ [tex]25200=7500(1+\frac{5.25}{100} )^{t}[/tex]

⇒ [tex]3.36=(1+0.0525)^{t}[/tex]

⇒ [tex]3.36=(1.0525)^{t}[/tex]

taking log both sides, we get

⇒ [tex]ln(3.36)=ln(1.0525^{t})[/tex]

⇒ [tex]1.21194=t\times ln(1.0525)[/tex]

⇒ [tex]1.21194=t\times 0.05117[/tex]

⇒ [tex]t=23.7[/tex]

Therefore,

After [tex]23.7\ years[/tex] the amount [tex]7500\ dollars[/tex] will reach to [tex]25200\ dollars[/tex].

So, the time taken for reaching 7500 to 25200 is 2.9 years.

To understand the calculations, check below

Compound Intrest:

The formula for finding the amount with the help of compound interest is,

[tex]A=P(1+r)^t[/tex]

Given that,

[tex]Amount=25200\\r=5.25\%=0.525\\Principal=7500[/tex]

Now, substituting the given values into the above formula we get,

[tex]A=P(1+r)^t\\25200=7500(1+0.525)^t\\3.36=(1.525)^t\\[/tex]

Taking log both sides we get,

[tex]ln(3.36)=tln(1.525)\\1.212=t\times 0.422\\t=2.9[/tex]

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