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GATE 2022 ST – Question 30

Probability · Random Variables and Transforms · 1 mark · Numerical answer

X has MGF M(t),mean 1/2 and variance 1/4. Y has MGF H(t)=[(3/4)e^(2t)+1/4]M(t) near zero. Find Var Y as an integer.

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Correct answer: 1 to 1

Explanation

The prefactor is the MGF of an independent variable Z equal to 2 with probability 3/4 and 0 with probability 1/4. Thus Y has the law of X+Z. Var Z=4(3/4)(1/4)=3/4,so Var Y=1/4+3/4=**1**.

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