NCEES Mathematics 4 — Questions and Answers
Question 1: Solve the differential equation y'' + 4y = 0. The general solution is:
- y = C₁cos(2x) + C₂sin(2x) (Correct answer)
- y = C₁e^(2x) + C₂e^(-2x)
- y = (C₁ + C₂x)e^(2x)
- y = C₁cos(4x) + C₂sin(4x)
Correct answer: y = C₁cos(2x) + C₂sin(2x)
The characteristic equation r² + 4 = 0 gives r = ±2i, leading to a sinusoidal solution.
Question 2: The Fourier series of a function requires the function to be:
- Periodic (Correct answer)
- Continuous everywhere
- Differentiable everywhere
- Always positive
Correct answer: Periodic
Fourier series represent periodic functions, though convergence conditions (Dirichlet conditions) may vary.
Question 3: What is the cross product A × B if A = (1, 0, 0) and B = (0, 1, 0)?
- (0, 0, 1) (Correct answer)
- (1, 1, 0)
- (0, 0, -1)
- (1, 0, 1)
Correct answer: (0, 0, 1)
i × j = k, so (1,0,0) × (0,1,0) = (0,0,1).
Question 4: A binomial distribution with n = 10 and p = 0.3 has a mean of:
- 3 (Correct answer)
- 0.3
- 7
- 2.1
Correct answer: 3
The mean of a binomial distribution is μ = np = 10 × 0.3 = 3.
Question 5: Which method is best suited for finding roots of a nonlinear equation numerically?
- Newton-Raphson method (Correct answer)
- Gaussian elimination
- Simpson's rule
- Euler's method
Correct answer: Newton-Raphson method
Newton-Raphson is an iterative root-finding method for nonlinear equations.
Question 6: The Divergence Theorem relates a volume integral of divergence to:
- A surface integral over the bounding surface (Correct answer)
- A line integral around the boundary
- A curl integral inside the volume
- Another volume integral
Correct answer: A surface integral over the bounding surface
Gauss's Divergence Theorem states ∭∇·F dV = ∯F·dS over the closed bounding surface.
Question 7: If the standard deviation of a data set is 0, what can be concluded?
- All values are identical (Correct answer)
- The mean is 0
- The data is normally distributed
- There is only one data point
Correct answer: All values are identical
A standard deviation of 0 means there is no variability; all values equal the mean.
Solve the differential equation y'' + 4y = 0.
The general solution is: