Interest Rate Calculator | CFA® Level 1 Exam Preparation

Calculate Annual Interest Rate for Series of Deposits

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Question

What annual interest rate, compounded annually, would cause a series of 10 deposits of $1,000 to accumulate to $18,000, if the first deposit is made one year from today?

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A. B. C. D. E.

B

On the BAII Plus, press 10 N, 0 PV, 1000 PMT, 18000 +/- FV, CPT I/Y. On the HP12C, press 10 n, 0 PV, 1000 PMT, 18000 CHS FV, i. Make sure that the BAII

Plus has the P/Y value set to 1.

To solve this problem, we can use the formula for the future value of an annuity:

FV = P * [(1 + r)^n - 1] / r

Where: FV = Future value of the annuity P = Periodic payment amount r = Annual interest rate n = Number of periods

In this case, we have 10 deposits of $1,000, so P = $1,000 and n = 10. We need to find the annual interest rate (r) that will result in a future value (FV) of $18,000.

Let's plug in the values into the formula and solve for r:

$18,000 = $1,000 * [(1 + r)^10 - 1] / r

To solve this equation, we can use trial and error or a financial calculator. However, since we have answer choices available, we can simply test each option to see which one satisfies the equation.

Let's start by testing option A: 14.49%. Plugging in r = 0.1449 into the formula:

$18,000 = $1,000 * [(1 + 0.1449)^10 - 1] / 0.1449

Evaluating the right side of the equation:

$18,000 = $1,000 * [(1.1449)^10 - 1] / 0.1449 $18,000 = $1,000 * [2.7135 - 1] / 0.1449 $18,000 = $1,000 * 1.7135 / 0.1449 $18,000 = $17,135.40

Option A does not give us the desired result. Let's move on to option B: 12.52%.

$18,000 = $1,000 * [(1 + 0.1252)^10 - 1] / 0.1252 $18,000 = $1,000 * [2.829 - 1] / 0.1252 $18,000 = $1,000 * 1.829 / 0.1252 $18,000 = $14,583.47

Option B also does not give us the desired result. Let's move on to option C: 12.69%.

$18,000 = $1,000 * [(1 + 0.1269)^10 - 1] / 0.1269 $18,000 = $1,000 * [2.867 - 1] / 0.1269 $18,000 = $1,000 * 1.867 / 0.1269 $18,000 = $14,706.78

Option C does not give us the desired result either. Let's try option D: 11.84%.

$18,000 = $1,000 * [(1 + 0.1184)^10 - 1] / 0.1184 $18,000 = $1,000 * [2.597 - 1] / 0.1184 $18,000 = $1,000 * 1.597 / 0.1184 $18,000 = $13,502.68

Option D also does not give us the desired result. Finally, let's try option E: 35.82%.

$18,000 = $1,000 * [(1 + 0.3582)^10 - 1] / 0.3582 $18,000 = $1,000 * [6.119 - 1] /