Question

Is my answer correct?

Answer 1

9514 1404 393

Answer:

  yes

Step-by-step explanation:

By the "rule of 72", the amount will be doubled in 72/I years, where I is the annual interest rate in percent. That is, it can be estimated to take 72/4 = 18 years to double the $240 investment to $480. It would take another 18 years to double it again to $960. So, to achieve a balance of $1500 will be expected to take more than 36 years. The only reasonable answer choice is the one you have selected.

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The exact solution is ...

  log (1500/240)/log(1 +0.04) ≈ 46.72 years ≈ 47 years.