GATE ME concept:standard-deviation PYQs & Answers

Questions 1–3 of 3. Imported answers require independent review unless marked reviewed.

The sum of two normally distributed random variables X and Y is

Your answerChoose one option.

always normally distributed

normally distributed, only if X and Y are independent

normally distributed, only if X and Y have the same standard deviation

normally distributed, only if X and Y have the same mean

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The lengths of a large stock of titanium rods follow a normal distribution with a mean (

) of 440 mm and a standard deviation (

) of 1 mm. What is the percentage of rods whose lengths lie between 438 mm and 441 mm?

Your answerChoose one option.

81.85%

68.4%

99.75%

86.64%

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Let

be two independent normal random variables with means

and standard deviations

, respectively. Consider

;

. Then,

Your answerChoose one option.

Y is normally distributed with mean 0 and variance 1

Y is normally distributed with mean 0 and variance 5

Y has mean 0 and variance 5, but is NOT normally distributed

Y has mean 0 and variance 1, but is NOT normally distributed

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GATE ME concept:standard-deviation PYQs