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NCEES FE Other Disciplines Engineering Mathematics: practice questions

NCEES FE Other Disciplines · USA · NCEES

Original practice questions written to the published syllabus · not past papers
10worked here, free
58written to this exam in this subject
16syllabus units

What this subject covers

The algebra, calculus, differential equations and numerical methods used in every numerical question of the degree. GATE AG gives it a fixed block of marks every year.

In the exams: GATE AG Section 1, about 12–13 marks a year (2019–26); ICAR AIEEA-PG Unit I; NCEES FE 8–12 questions; allied subject in PRC ABE

What NCEES FE Other Disciplines asks from it

NCEES FE Other Disciplines

About 8–12 mathematics questions answered with the NCEES FE Reference Handbook available on screen. Formulas are given, so the test is choosing and applying the right one quickly: derivatives and integrals, vector operations, differential equations, matrix operations and numerical methods such as Newton's method and the trapezoidal rule. Probability and statistics are a separate section of the exam.

Where the 58 questions fall

How our questions for NCEES FE Other Disciplines spread across the units of Engineering Mathematics. Difficulty: 22 easy, 24 medium, 12 hard.

Higher-order linear ordinary differential equations5
Laplace transforms5
Numerical solution of equations: bisection and Newton-Raphson5
Numerical integration: trapezoidal and Simpson's rules5
Limits, continuity and partial derivatives4
Vector calculus: gradient, divergence and curl4
Line, surface and volume integrals: Green, Stokes and Gauss theorems4
Partial differential equations: Laplace, heat and wave equations4
Numerical solution of ODEs: Euler and Runge-Kutta methods4
Matrices, determinants and systems of linear equations3
Maxima and minima of functions of several variables3
Sequences, series and convergence3
Taylor, Maclaurin and Fourier series3
First-order ordinary differential equations3
Eigenvalues, eigenvectors and the Cayley-Hamilton theorem2
Euler's theorem on homogeneous functions1

10 practice questions, worked

Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.

1 · Matrices, determinants and systems of linear equations · easy

What is the inverse of the 2×2 matrix [[4, 7], [2, 6]]?

  1. (1/38)[[6, −7], [−2, 4]]
  2. (1/10)[[6, 7], [2, 4]]
  3. (1/10)[[6, −7], [−2, 4]]
  4. (1/10)[[4, −7], [−2, 6]]
Answer and working

C. (1/10)[[6, −7], [−2, 4]]

det = 4·6 − 7·2 = 10. For [[a, b], [c, d]] the inverse is (1/det)[[d, −b], [−c, a]]: swap the diagonal and negate the off-diagonal. Forgetting to negate b and c gives [[6, 7], [2, 4]]; not swapping a and d gives [[4, −7], [−2, 6]]; adding instead of subtracting in the determinant gives 38.

Further reading: Kreyszig, Advanced Engineering Mathematics

2 · Matrices, determinants and systems of linear equations · medium

A is a 3×3 matrix with det(A) = 5. What is det(2A⁻¹)?

  1. 40
  2. 2/5
  3. 10
  4. 8/5
Answer and working

D. 8/5

det(kA) = kⁿ det(A) for an n×n matrix, and det(A⁻¹) = 1/det(A). So det(2A⁻¹) = 2³ × (1/5) = 8/5. Using k instead of k³ gives 2/5; 40 is det(2A), forgetting the inverse; 10 multiplies 2 by 5.

Further reading: Grewal, Higher Engineering Mathematics

3 · Limits, continuity and partial derivatives · medium

z = x²y with x = t² and y = t³. What is dz/dt at t = 1?

  1. 7
  2. 2
  3. 6
  4. 5
Answer and working

A. 7

Chain rule: dz/dt = (∂z/∂x)(dx/dt) + (∂z/∂y)(dy/dt) = (2xy)(2t) + (x²)(3t²). At t = 1, x = y = 1: 2·2 + 1·3 = 7. Check: z = t⁷, dz/dt = 7t⁶ = 7. Taking only one path gives 4 or 3; 5 and 6 come from adding exponents wrongly.

Further reading: Kreyszig, Advanced Engineering Mathematics

4 · Limits, continuity and partial derivatives · medium

The radius of a circular centre-pivot field is measured as 50 m with a possible error of 0.5 m. Using differentials, what is the approximate percentage error in the computed area?

  1. 0.5%
  2. 4%
  3. 1%
  4. 2%
Answer and working

D. 2%

A = πr², so dA/A = 2 dr/r = 2 × 0.5/50 = 0.02 = 2%. The relative error of rⁿ is n times the relative error of r. 1% forgets the factor 2 from the square; 4% squares the 2 as well.

Further reading: Grewal, Higher Engineering Mathematics

5 · Sequences, series and convergence · easy

The p-series Σ 1/nᵖ (n = 1 to ∞) converges if and only if

  1. p ≥ 1
  2. p < 1
  3. p > 1
  4. p > 0
Answer and working

C. p > 1

By the integral test, ∫ dx/xᵖ from 1 to ∞ is finite only for p > 1. At p = 1 it is the harmonic series, which diverges, so p ≥ 1 is wrong. p > 0 only makes the terms tend to zero, which is not enough.

Further reading: Kreyszig, Advanced Engineering Mathematics

6 · Line, surface and volume integrals: Green, Stokes and Gauss theorems · medium

Evaluate ∫₀¹ ∫₀ˣ xy dy dx.

  1. 1/8
  2. 1/2
  3. 1/6
  4. 1/4
Answer and working

A. 1/8

Inner: ∫₀ˣ xy dy = x·x²/2 = x³/2. Outer: ∫₀¹ x³/2 dx = 1/8. 1/4 comes from integrating y over 0 to 1 (wrong inner limit), giving ∫ x/2 dx = 1/4.

Further reading: Kreyszig, Advanced Engineering Mathematics

7 · Higher-order linear ordinary differential equations · medium

What is a particular integral of y'' − 3y' + 2y = e^(3x)?

  1. −e^(3x)/2
  2. e^(3x)/2
  3. e^(3x)
  4. e^(3x)/20
Answer and working

B. e^(3x)/2

For e^(ax) with f(a) ≠ 0, PI = e^(ax)/f(a). f(m) = m² − 3m + 2, f(3) = 9 − 9 + 2 = 2, so PI = e^(3x)/2. 1/20 uses 9 + 9 + 2 (sign slip on −3m).

Further reading: Grewal, Higher Engineering Mathematics

8 · Laplace transforms · easy

What is the Laplace transform of t²?

  1. 2/s²
  2. 1/s³
  3. 1/s²
  4. 2/s³
Answer and working

D. 2/s³

L{tⁿ} = n!/s^(n+1). For n = 2: 2!/s³ = 2/s³. 1/s³ forgets the n!; 2/s² uses sⁿ instead of s^(n+1).

Further reading: Kreyszig, Advanced Engineering Mathematics

9 · Numerical integration: trapezoidal and Simpson's rules · medium

Using the trapezoidal rule with h = 0.5, what is ∫₀¹ x² dx?

  1. 0.250
  2. 0.3333
  3. 0.375
  4. 0.750
Answer and working

C. 0.375

Points x = 0, 0.5, 1 → f = 0, 0.25, 1. T = (h/2)[f₀ + 2f₁ + f₂] = 0.25 × (0 + 0.5 + 1) = 0.375 (exact 1/3; the rule over-estimates a convex function). 0.750 forgets the h/2 and uses h; 0.3333 is the exact value, which Simpson's rule would give.

Further reading: Chapra and Canale, Numerical Methods for Engineers

10 · Numerical integration: trapezoidal and Simpson's rules · hard

A storm hydrograph at a watershed outlet is read every hour: 0, 5, 12, 8, 3 and 0 m³/s. Using the trapezoidal rule, what is the runoff volume?

  1. 100,800 m³
  2. 1,680 m³
  3. 28 m³
  4. 201,600 m³
Answer and working

A. 100,800 m³

h = 1 h = 3,600 s. V = (h/2)[Q₀ + Q₅ + 2(Q₁ + Q₂ + Q₃ + Q₄)] = 1,800 × 2 × 28 = 100,800 m³. Forgetting to convert hours to seconds gives 28; converting 1 h to 60 s gives 1,680; using h instead of h/2 doubles the result to 201,600 m³.

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Engineering MathematicsThe full study manual, free NCEES FE Other DisciplinesFormat, sections and how it has changed

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