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CUET-PG Real Analysis for Statistics: practice questions

CUET-PG - Statistics · India · National Testing Agency

Original practice questions written to the published syllabus · not past papers
9worked here, free
26written to this exam in this subject
11syllabus units

What this subject covers

The rigorous calculus behind limits theorems and estimation: sequences, series, continuity, differentiability and Riemann integration, at the level GATE Statistics and JAM Mathematical Statistics examine and that measure-theoretic probability later builds on.

In the exams: GATE ST 'Calculus' section (heavy); IIT JAM MS mathematics component (heavy); AIEEA-PG Group 07 Unit II-III mathematics (present); ISI admission tests (heavy); UPSC ISS Statistics I (light)

Where the 26 questions fall

How our questions for CUET-PG spread across the units of Real Analysis for Statistics. Difficulty: 23 easy, 3 medium, 0 hard.

Sets, countability and the real number system4
Sequences: convergence, monotone and Cauchy sequences3
Limits, continuity and uniform continuity3
L'Hospital's rule and indeterminate forms3
Series: tests of convergence, absolute and conditional convergence2
Power series and radius of convergence2
Differentiability, Rolle's and mean value theorems, Taylor's theorem2
Riemann integration and improper integrals2
Gamma and beta functions2
Double and triple integrals and change of variables2
Functions of several variables: partial derivatives, Jacobians, maxima, minima and Lagrange multipliers1

9 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 · Sets, countability and the real number system · easy

What are the supremum and infimum of S = {1 − 1/n : n = 1, 2, 3, …}?

  1. sup 1 (attained), inf 0 (not attained)
  2. sup 1, inf −1
  3. sup 1 (not attained), inf 0 (attained)
  4. sup ∞, inf 0
Answer and working

C. sup 1 (not attained), inf 0 (attained)

Terms are 0, 1/2, 2/3, …, increasing towards 1 without reaching it; the minimum 0 occurs at n = 1.

Further reading: Rudin, Principles of Mathematical Analysis (1976); Bartle and Sherbert, Introduction to Real Analysis (2011); Apostol, Mathematical Analysis (1974); Casella and Berger, Statistical Inference (2002)

2 · Sequences: convergence, monotone and Cauchy sequences · easy

Which sequence diverges?

  1. (−1)ⁿ
  2. 1/n
  3. (−1)ⁿ/n
  4. n/(n + 1)
Answer and working

A. (−1)ⁿ

(−1)ⁿ has subsequences tending to 1 and −1. The others tend to 0, 0 and 1.

Further reading: Rudin, Principles of Mathematical Analysis (1976); Bartle and Sherbert, Introduction to Real Analysis (2011); Apostol, Mathematical Analysis (1974); Casella and Berger, Statistical Inference (2002)

3 · Sequences: convergence, monotone and Cauchy sequences · medium

Which statement is true for real sequences?

  1. Every bounded sequence converges
  2. Every bounded sequence has a convergent subsequence
  3. Every convergent sequence is monotone
  4. Every monotone sequence converges
Answer and working

B. Every bounded sequence has a convergent subsequence

Bolzano–Weierstrass gives the first. Monotone sequences converge only if bounded; convergent sequences need not be monotone.

Further reading: Rudin, Principles of Mathematical Analysis (1976); Bartle and Sherbert, Introduction to Real Analysis (2011); Apostol, Mathematical Analysis (1974); Casella and Berger, Statistical Inference (2002)

4 · Series: tests of convergence, absolute and conditional convergence · easy

The p-series Σ1/nᵖ converges if and only if:

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

A. p > 1

At p = 1 it is the divergent harmonic series; the integral test gives convergence exactly for p > 1.

Further reading: Rudin, Principles of Mathematical Analysis (1976); Bartle and Sherbert, Introduction to Real Analysis (2011); Apostol, Mathematical Analysis (1974); Casella and Berger, Statistical Inference (2002)

5 · Power series and radius of convergence · easy

What is the radius of convergence of Σxⁿ/n!?

  1. 1
  2. 0
  3. ∞
  4. e
Answer and working

C. ∞

aₙ/aₙ₊₁ = n + 1 → ∞; the series is eˣ for all x.

Further reading: Rudin, Principles of Mathematical Analysis (1976); Bartle and Sherbert, Introduction to Real Analysis (2011); Apostol, Mathematical Analysis (1974); Casella and Berger, Statistical Inference (2002)

6 · Power series and radius of convergence · easy

The radius of convergence of Σn!xⁿ is:

  1. 1
  2. ∞
  3. 0
  4. e
Answer and working

C. 0

aₙ₊₁/aₙ = n + 1 → ∞, so the series converges only at x = 0.

Further reading: Rudin, Principles of Mathematical Analysis (1976); Bartle and Sherbert, Introduction to Real Analysis (2011); Apostol, Mathematical Analysis (1974); Casella and Berger, Statistical Inference (2002)

7 · L'Hospital's rule and indeterminate forms · easy

What is lim (1 − cos x)/x² as x → 0?

  1. 0
  2. 1
  3. 2
  4. 1/2
Answer and working

D. 1/2

Applying L'Hospital twice: sin x/(2x) → 1/2; or 1 − cos x ≈ x²/2.

Further reading: Rudin, Principles of Mathematical Analysis (1976); Bartle and Sherbert, Introduction to Real Analysis (2011); Apostol, Mathematical Analysis (1974); Casella and Berger, Statistical Inference (2002)

8 · L'Hospital's rule and indeterminate forms · easy

What is lim (ln x)/x as x → ∞?

  1. 1
  2. ∞
  3. e
  4. 0
Answer and working

D. 0

L'Hospital gives (1/x)/1 → 0: logarithms grow more slowly than x.

Further reading: Rudin, Principles of Mathematical Analysis (1976); Bartle and Sherbert, Introduction to Real Analysis (2011); Apostol, Mathematical Analysis (1974); Casella and Berger, Statistical Inference (2002)

9 · Riemann integration and improper integrals · easy

What is ∫₀¹ ln x dx?

  1. 0
  2. 1
  3. −1
  4. Diverges
Answer and working

C. −1

x ln x − x from 0 to 1 = (0 − 1) − 0 = −1; the integral is improper at 0 but converges.

Further reading: Rudin, Principles of Mathematical Analysis (1976); Bartle and Sherbert, Introduction to Real Analysis (2011); Apostol, Mathematical Analysis (1974); Casella and Berger, Statistical Inference (2002)

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Read the subject

Real Analysis for StatisticsThe full study manual, free CUET-PGFormat, sections and how it has changed

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Real Analysis for Statistics for other exams

GATE · IndiaIIT JAM · India

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