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How long must $5600 be in a bank at 7% compounded annually to become $11,016.05? (Round to the nearest year.)

A) 6 years
B) 7 years
C) 8 years
D) 9 years
E) 10 years

User Aidonsnous
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1 Answer

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Final answer:

To find out how long $5600 must be deposited at an annual rate of 7% to grow to $11,016.05, you use the compound interest formula. Calculating with the given figures yields approximately 10 years, making the correct answer option E) 10 years.

Step-by-step explanation:

To determine how long $5600 must be in a bank at 7% compounded annually to become $11,016.05, we can use the formula for compound interest, A = P(1 + r/n)^(nt), where:

  • A is the amount of money accumulated after n years, including interest.
  • P is the principal amount (the initial amount of money).
  • r is the annual interest rate (decimal).
  • n is the number of times that interest is compounded per year.
  • t is the time the money is invested for, in years.

In this case:

  • A = $11,016.05
  • P = $5600
  • r = 7% or 0.07
  • n = 1 (compounded annually)

We want to find t, so we rearrange the formula:

t = log(A/P) / (n × log(1 + r/n))

Substituting the values in:

t = log(11016.05/5600) / (1 × log(1 + 0.07))

After calculating, we find that t is approximately 10 years, which matches option E. Therefore, $5600 needs to be invested for approximately 10 years at an annual compound rate of 7% to grow to $11,016.05.

E) 10 years rounded to the nearest year.