6000 dollars is invested in a bank account at an interest rate of 6 per cent per year, compounded continuously. Meanwhile, 16000 dollars is invested in a bank account at an interest rate of 5 percent compounded annually. To the nearest year, when will the two accounts have the same balance?

Respuesta :

9514 1404 393

Answer:

  87 years

Step-by-step explanation:

The balance (A) in the continuously compounded account will be ...

  A = P·e^(rt)

  A = 6000·e^(0.06t)

__

The balance (A) in the annually compounded account will be ...

  A = P(1 +r)^t

  A = 16000(1 +0.05)^t

These balances are equal when ...

  6000·e^(0.06t) = 16000(1.05^t)

We can divide by 6000 to simplify this a little bit.

  e^(0.06t) = 8/3(1.05^t)

Taking the natural logarithm gives ...

  0.06t = ln(8/3) +t·ln(1.05)

  t(0.06 -ln(1.05)) = ln(8/3) . . . . subtract t·ln(1.05) and factor)

  t = ln(8/3)/(0.06 -ln(1.05)) ≈ 0.980829/0.0112098 ≈ 87.497

Rounded to the nearest year, the balances will be the same after 87 years.

_____

The balances will be about 1.14 million dollars.

Ver imagen sqdancefan
ACCESS MORE
ACCESS MORE
ACCESS MORE
ACCESS MORE