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GATE 2023 ST – Question 22

Estimation · Point Estimation and Consistency · 1 mark · Multiple choice

X has exponential density e^(−x/λ)/λ for x>0,λ>0 unknown. Y₁,…,Y_n are iid with the distribution of X² and Ȳ is their mean. Which is the method-of-moments estimator of λ?

  1. √(Ȳ/2)
  2. √Ȳ
  3. (1/2)√Ȳ
  4. 2√Ȳ

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Correct answer: (A) √(Ȳ/2)

Explanation

The first Y moment is E Y=E X²=2λ². Equate this to Ȳ and take the positive root,obtaining **√(Ȳ/2), A**.

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