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Non-Annual Compounding

Engineering Economics · FE Reference Handbook section

Engineering Economics
1 formulas
10 exam-style examples
~47 min
All Engineering Economics lectures

Core formulas for this FE topic

Definitions, applicability, units, assumptions and worked examples for each relation.

Worked exam-style examples

The four ways this section is written on the real exam — thoughts first, then equations, then substitution.

Example 1
Uniform-series present worth — solve for present worth — Non-Annual Compounding

A engineering economics problem uses Uniform-series present worth. Given annual amount (A) = 48,300 $/yr; interest rate (i) = 0.0250 1/yr; years (n) = 25.0000 yr, determine the present worth (P) in $.

Given

  • annual amount (A) = 48,300 $/yr

  • interestrate(i)=0.02501/yrinterest rate (i) = 0.0250 1/yr
  • years(n)=25.0000yryears (n) = 25.0000 yr

Find

present worth (P), in $

Start with the thinking

  • The governing relation printed in this handbook section is Uniform-series present worth.
  • Everything except P is given, so isolate P symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Engineering Economics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]
  2. Step 2 — Rearrange the relation so that P stands alone on the left-hand side.

  3. Step 3 — List the givens: annual amount (A) = 48,300 $/yr, interest rate (i) = 0.0250 1/yr, years (n) = 25.0000 yr.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    P=889897 $P = 889897\ \text{\$}
  6. Step 6 — Check: returning P = 889,897 $ to

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]

    reproduces the given quantities, and both sides carry the same units.

Answer:
P=889897 $P = 889897\ \text{\$}

Why the other options are there

  • 1,779,795 — kept a factor of two that cancels in the correct rearrangement.
  • 444,949 — dropped that same factor in the other direction.
  • 978,887 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Engineering Economics → Non-Annual Compounding

Example 2
Uniform-series present worth — solve for annual amount — Non-Annual Compounding (2)

A engineering economics problem uses Uniform-series present worth. Given interest rate (i) = 0.0550 1/yr; years (n) = 7.0000 yr; present worth (P) = 316,023 $, determine the annual amount (A) in $/yr.

Given

  • interestrate(i)=0.05501/yrinterest rate (i) = 0.0550 1/yr
  • years(n)=7.0000yryears (n) = 7.0000 yr
  • present worth (P) = 316,023 $

Find

annual amount (A), in $/yr

Start with the thinking

  • The governing relation printed in this handbook section is Uniform-series present worth.
  • Everything except A is given, so isolate A symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Engineering Economics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]
  2. Step 2 — Rearrange the relation so that A stands alone on the left-hand side.

  3. Step 3 — List the givens: interest rate (i) = 0.0550 1/yr, years (n) = 7.0000 yr, present worth (P) = 316,023 $.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    A=55609 $/yrA = 55609\ \text{\$/yr}
  6. Step 6 — Check: returning A = 55,609 $/yr to

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]

    reproduces the given quantities, and both sides carry the same units.

Answer:
A=55609 $/yrA = 55609\ \text{\$/yr}

Why the other options are there

  • 111,218 — kept a factor of two that cancels in the correct rearrangement.
  • 27,804 — dropped that same factor in the other direction.
  • 61,170 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Engineering Economics → Non-Annual Compounding

Example 3
Uniform-series present worth — solve for present worth (case 2) — Non-Annual Compounding (3)

A engineering economics problem uses Uniform-series present worth. Given annual amount (A) = 47,700 $/yr; interest rate (i) = 0.0750 1/yr; years (n) = 25.0000 yr, determine the present worth (P) in $.

Given

  • annual amount (A) = 47,700 $/yr

  • interestrate(i)=0.07501/yrinterest rate (i) = 0.0750 1/yr
  • years(n)=25.0000yryears (n) = 25.0000 yr

Find

present worth (P), in $

Start with the thinking

  • The governing relation printed in this handbook section is Uniform-series present worth.
  • Everything except P is given, so isolate P symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Engineering Economics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]
  2. Step 2 — Rearrange the relation so that P stands alone on the left-hand side.

  3. Step 3 — List the givens: annual amount (A) = 47,700 $/yr, interest rate (i) = 0.0750 1/yr, years (n) = 25.0000 yr.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    P=531709 $P = 531709\ \text{\$}
  6. Step 6 — Check: returning P = 531,709 $ to

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]

    reproduces the given quantities, and both sides carry the same units.

Answer:
P=531709 $P = 531709\ \text{\$}

Why the other options are there

  • 1,063,419 — kept a factor of two that cancels in the correct rearrangement.
  • 265,855 — dropped that same factor in the other direction.
  • 584,880 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Engineering Economics → Non-Annual Compounding

Example 4
Uniform-series present worth — solve for annual amount (case 2) — Non-Annual Compounding (4)

A engineering economics problem uses Uniform-series present worth. Given interest rate (i) = 0.1000 1/yr; years (n) = 29.0000 yr; present worth (P) = 461,833 $, determine the annual amount (A) in $/yr.

Given

  • interestrate(i)=0.10001/yrinterest rate (i) = 0.1000 1/yr
  • years(n)=29.0000yryears (n) = 29.0000 yr
  • present worth (P) = 461,833 $

Find

annual amount (A), in $/yr

Start with the thinking

  • The governing relation printed in this handbook section is Uniform-series present worth.
  • Everything except A is given, so isolate A symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Engineering Economics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]
  2. Step 2 — Rearrange the relation so that A stands alone on the left-hand side.

  3. Step 3 — List the givens: interest rate (i) = 0.1000 1/yr, years (n) = 29.0000 yr, present worth (P) = 461,833 $.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    A=49291 $/yrA = 49291\ \text{\$/yr}
  6. Step 6 — Check: returning A = 49,291 $/yr to

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]

    reproduces the given quantities, and both sides carry the same units.

Answer:
A=49291 $/yrA = 49291\ \text{\$/yr}

Why the other options are there

  • 98,581 — kept a factor of two that cancels in the correct rearrangement.
  • 24,645 — dropped that same factor in the other direction.
  • 54,220 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Engineering Economics → Non-Annual Compounding

Example 5
Uniform-series present worth — solve for present worth (case 3) — Non-Annual Compounding (5)

A engineering economics problem uses Uniform-series present worth. Given annual amount (A) = 41,800 $/yr; interest rate (i) = 0.0300 1/yr; years (n) = 17.0000 yr, determine the present worth (P) in $.

Given

  • annual amount (A) = 41,800 $/yr

  • interestrate(i)=0.03001/yrinterest rate (i) = 0.0300 1/yr
  • years(n)=17.0000yryears (n) = 17.0000 yr

Find

present worth (P), in $

Start with the thinking

  • The governing relation printed in this handbook section is Uniform-series present worth.
  • Everything except P is given, so isolate P symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Engineering Economics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]
  2. Step 2 — Rearrange the relation so that P stands alone on the left-hand side.

  3. Step 3 — List the givens: annual amount (A) = 41,800 $/yr, interest rate (i) = 0.0300 1/yr, years (n) = 17.0000 yr.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    P=550344 $P = 550344\ \text{\$}
  6. Step 6 — Check: returning P = 550,344 $ to

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]

    reproduces the given quantities, and both sides carry the same units.

Answer:
P=550344 $P = 550344\ \text{\$}

Why the other options are there

  • 1,100,688 — kept a factor of two that cancels in the correct rearrangement.
  • 275,172 — dropped that same factor in the other direction.
  • 605,378 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Engineering Economics → Non-Annual Compounding

Example 6
Uniform-series present worth — solve for annual amount (case 3) — Non-Annual Compounding (6)

A engineering economics problem uses Uniform-series present worth. Given interest rate (i) = 0.0750 1/yr; years (n) = 23.0000 yr; present worth (P) = 102,243 $, determine the annual amount (A) in $/yr.

Given

  • interestrate(i)=0.07501/yrinterest rate (i) = 0.0750 1/yr
  • years(n)=23.0000yryears (n) = 23.0000 yr
  • present worth (P) = 102,243 $

Find

annual amount (A), in $/yr

Start with the thinking

  • The governing relation printed in this handbook section is Uniform-series present worth.
  • Everything except A is given, so isolate A symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Engineering Economics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]
  2. Step 2 — Rearrange the relation so that A stands alone on the left-hand side.

  3. Step 3 — List the givens: interest rate (i) = 0.0750 1/yr, years (n) = 23.0000 yr, present worth (P) = 102,243 $.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    A=9461 $/yrA = 9461\ \text{\$/yr}
  6. Step 6 — Check: returning A = 9,461 $/yr to

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]

    reproduces the given quantities, and both sides carry the same units.

Answer:
A=9461 $/yrA = 9461\ \text{\$/yr}

Why the other options are there

  • 18,922 — kept a factor of two that cancels in the correct rearrangement.
  • 4,731 — dropped that same factor in the other direction.
  • 10,407 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Engineering Economics → Non-Annual Compounding

Example 7
Uniform-series present worth — solve for present worth (case 4) — Non-Annual Compounding (7)

A engineering economics problem uses Uniform-series present worth. Given annual amount (A) = 3,100 $/yr; interest rate (i) = 0.1000 1/yr; years (n) = 23.0000 yr, determine the present worth (P) in $.

Given

  • annual amount (A) = 3,100 $/yr

  • interestrate(i)=0.10001/yrinterest rate (i) = 0.1000 1/yr
  • years(n)=23.0000yryears (n) = 23.0000 yr

Find

present worth (P), in $

Start with the thinking

  • The governing relation printed in this handbook section is Uniform-series present worth.
  • Everything except P is given, so isolate P symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Engineering Economics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]
  2. Step 2 — Rearrange the relation so that P stands alone on the left-hand side.

  3. Step 3 — List the givens: annual amount (A) = 3,100 $/yr, interest rate (i) = 0.1000 1/yr, years (n) = 23.0000 yr.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    P=27538 $P = 27538\ \text{\$}
  6. Step 6 — Check: returning P = 27,538 $ to

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]

    reproduces the given quantities, and both sides carry the same units.

Answer:
P=27538 $P = 27538\ \text{\$}

Why the other options are there

  • 55,076 — kept a factor of two that cancels in the correct rearrangement.
  • 13,769 — dropped that same factor in the other direction.
  • 30,292 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Engineering Economics → Non-Annual Compounding

Example 8
Uniform-series present worth — solve for annual amount (case 4) — Non-Annual Compounding (8)

A engineering economics problem uses Uniform-series present worth. Given interest rate (i) = 0.0450 1/yr; years (n) = 10.0000 yr; present worth (P) = 478,105 $, determine the annual amount (A) in $/yr.

Given

  • interestrate(i)=0.04501/yrinterest rate (i) = 0.0450 1/yr
  • years(n)=10.0000yryears (n) = 10.0000 yr
  • present worth (P) = 478,105 $

Find

annual amount (A), in $/yr

Start with the thinking

  • The governing relation printed in this handbook section is Uniform-series present worth.
  • Everything except A is given, so isolate A symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Engineering Economics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]
  2. Step 2 — Rearrange the relation so that A stands alone on the left-hand side.

  3. Step 3 — List the givens: interest rate (i) = 0.0450 1/yr, years (n) = 10.0000 yr, present worth (P) = 478,105 $.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    A=60422 $/yrA = 60422\ \text{\$/yr}
  6. Step 6 — Check: returning A = 60,422 $/yr to

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]

    reproduces the given quantities, and both sides carry the same units.

Answer:
A=60422 $/yrA = 60422\ \text{\$/yr}

Why the other options are there

  • 120,845 — kept a factor of two that cancels in the correct rearrangement.
  • 30,211 — dropped that same factor in the other direction.
  • 66,465 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Engineering Economics → Non-Annual Compounding

Example 9
Uniform-series present worth — solve for present worth (case 5) — Non-Annual Compounding (9)

A engineering economics problem uses Uniform-series present worth. Given annual amount (A) = 44,500 $/yr; interest rate (i) = 0.1150 1/yr; years (n) = 11.0000 yr, determine the present worth (P) in $.

Given

  • annual amount (A) = 44,500 $/yr

  • interestrate(i)=0.11501/yrinterest rate (i) = 0.1150 1/yr
  • years(n)=11.0000yryears (n) = 11.0000 yr

Find

present worth (P), in $

Start with the thinking

  • The governing relation printed in this handbook section is Uniform-series present worth.
  • Everything except P is given, so isolate P symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Engineering Economics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]
  2. Step 2 — Rearrange the relation so that P stands alone on the left-hand side.

  3. Step 3 — List the givens: annual amount (A) = 44,500 $/yr, interest rate (i) = 0.1150 1/yr, years (n) = 11.0000 yr.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    P=270104 $P = 270104\ \text{\$}
  6. Step 6 — Check: returning P = 270,104 $ to

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]

    reproduces the given quantities, and both sides carry the same units.

Answer:
P=270104 $P = 270104\ \text{\$}

Why the other options are there

  • 540,208 — kept a factor of two that cancels in the correct rearrangement.
  • 135,052 — dropped that same factor in the other direction.
  • 297,114 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Engineering Economics → Non-Annual Compounding

Example 10
Uniform-series present worth — solve for annual amount (case 5) — Non-Annual Compounding (10)

A engineering economics problem uses Uniform-series present worth. Given interest rate (i) = 0.0550 1/yr; years (n) = 16.0000 yr; present worth (P) = 259,390 $, determine the annual amount (A) in $/yr.

Given

  • interestrate(i)=0.05501/yrinterest rate (i) = 0.0550 1/yr
  • years(n)=16.0000yryears (n) = 16.0000 yr
  • present worth (P) = 259,390 $

Find

annual amount (A), in $/yr

Start with the thinking

  • The governing relation printed in this handbook section is Uniform-series present worth.
  • Everything except A is given, so isolate A symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Engineering Economics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]
  2. Step 2 — Rearrange the relation so that A stands alone on the left-hand side.

  3. Step 3 — List the givens: interest rate (i) = 0.0550 1/yr, years (n) = 16.0000 yr, present worth (P) = 259,390 $.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    A=24793 $/yrA = 24793\ \text{\$/yr}
  6. Step 6 — Check: returning A = 24,793 $/yr to

    P=A[(1+i)n−1]/[i(1+i)n]P = A [ (1+i)^n - 1 ] / [ i (1+i)^n ]

    reproduces the given quantities, and both sides carry the same units.

Answer:
A=24793 $/yrA = 24793\ \text{\$/yr}

Why the other options are there

  • 49,586 — kept a factor of two that cancels in the correct rearrangement.
  • 12,397 — dropped that same factor in the other direction.
  • 27,272 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Engineering Economics → Non-Annual Compounding

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