The GATE Grind

GATE 2023 ST – Question 61

Convergence of Random Variables · Laws of Large Numbers and Central Limit Theorem · 2 marks · Numerical answer

X_n are iid Exp(rate 1). Let Y_n=|X_(2n)−X_(2n−1)| and Ȳ_n=(Y₁+⋯+Y_n)/n. If √n[exp(−Ȳ_n)−e⁻¹] converges in distribution to N(0,σ²),find σ² to two decimals.

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: 0.12 to 0.16

Explanation

For y≥0,P(|X₁−X₂|>y)=2P(X₁>X₂+y)=e^(−y). Thus Y_n are iid Exp(1),mean and variance 1. The CLT and delta method with g(y)=e^(−y),g′(1)=−e⁻¹ give σ²=[g′(1)]²=e⁻²≈**0.14**.

More Laws of Large Numbers and Central Limit Theorem questions

All Laws of Large Numbers and Central Limit Theorem questions →