Dillon plans to invest $16,000 part at 4% simple interest and the rest at 5% simple interest what is the most he can invest at 4% and still be guaranteed at least 700 per year

Respuesta :

Answer:

The most Kyle can invest at 4% is $10000.

Step-by-step explanation:

To Determine:

What is the most he can invest at 4% and still be guaranteed at least $700 in interest per year?

Information Fetching and Solution Steps:

As

  • Dillon plans to invest $16,000 part at 4% simple interest
  • and the rest at 5% simple interest

So,

If Kyle has to invest $16,000. then the following equations can be established from the given data

[tex]x + y = 16,000[/tex]

[tex].04x + .05y = 700[/tex]

Multiplying the second equation by 100, we get,

[tex]4x+5y = 70000[/tex]

Multiplying the 1st equation i.e. [tex]x + y = 16,000[/tex] by 5

[tex]5x + 5y = 80000[/tex]

So, the equations become

[tex]\begin{bmatrix}5x+5y=80000\\ 4x+5y=70000\end{bmatrix}[/tex]

[tex]\mathrm{Isolate}\:x\:\mathrm{for}\:5x+5y=80000:\quad x=16000-y[/tex]

As

[tex]5x+5y=80000[/tex]

[tex]5x+5y-5y=80000-5y[/tex]

[tex]5x=80000-5y[/tex]

[tex]\frac{5x}{5}=\frac{80000}{5}-\frac{5y}{5}[/tex]

[tex]x=16000-y[/tex]

[tex]\mathrm{Subsititute\:}x=16000-y[/tex]

[tex]\begin{bmatrix}4\left(16000-y\right)+5y=70000\end{bmatrix}[/tex]

[tex]\mathrm{Isolate}\:y\:\mathrm{for}\:4\left(16000-y\right)+5y=70000:\quad y=6000[/tex]

As

[tex]4\left(16000-y\right)+5y=70000[/tex]

[tex]64000-4y+5y=70000[/tex]

[tex]64000+y=70000[/tex]

[tex]y=6000[/tex]

[tex]\mathrm{For\:}x=16000-y[/tex]

[tex]\mathrm{Subsititute\:}y=6000[/tex]

[tex]x=16000-6000[/tex]

[tex]x=10000[/tex] $

Therefore, the most Kyle can invest at 4% is $10000.

Keywords: interest rate, equation

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