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Mean, variance or standard deviation from a given probability table

This type of question, asked 9 times: May 2021 S1, 2 May 2023 S2, 3 May 2023 S2, 4 May 2023 S2, 9 May 2023 S1, 26 Apr 2025 S2, 15 Apr 2026 S2, 20 Apr 2026 S2, 19 May 2026 S2. All 10 questions below, oldest first.

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  1. Question 1

    May 2021 S1

    147
    A random variable XX has the probability distribution: X:1,2,3,4,5X: 1, 2, 3, 4, 5; P(X=x):K,2K,3K,2K,KP(X=x): K, 2K, 3K, 2K, K. Its variance is

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  2. Question 2

    2 May 2023 S2

    105
    The probability distribution of a random variable X is given by: X = 0,1,2,3,4 with P(X) = 0.4, 0.3, 0.1, 0.1, 0.1. Then the variance of X is

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  3. Question 3

    2 May 2023 S2

    148
    A random variable X has probability distribution: X=1,2,3,4 with P = 0.2, 0.4, 0.3, 0.1. The mean and variance of X are respectively

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  4. Question 4

    3 May 2023 S2

    113
    For the probability distribution
    X:-2-10123
    p(x):0.10.20.20.30.150.05
    Then Var(X)\text{Var}(X) is (Given: (0.25)2=0.0625, (0.35)2=0.1225, (0.45)2=0.2025(0.25)^2=0.0625,\,(0.35)^2=0.1225,\,(0.45)^2=0.2025)

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  5. Question 5

    4 May 2023 S2

    120
    If P(X=2)=0.3,P(X=3)=0.4,P(X=4)=0.3P(X=2)=0.3, P(X=3)=0.4, P(X=4)=0.3, then the variance of random variable X is

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  6. Question 6

    9 May 2023 S1

    104
    If X is a random variable with distribution given below: X=xi: 0, 1, 2, 3; P(X=xi): k, 3k, 3k, k Then the value of k and its variance are respectively given by

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  7. Question 7

    26 Apr 2025 S2

    133
    A random variable X has the following probability distribution :
    X=xX = x1234
    P(X=x)P(X = x)0.10.20.30.4
    The mean and standard deviation of XX are respectively

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  8. Question 8

    15 Apr 2026 S2

    98
    For the following probability distribution, the standard deviation of the random variable X is
    X234
    p(X=xx)0.20.50.3

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  9. Question 9

    20 Apr 2026 S2

    99
    For the following probability distribution of a random variable XX, the Expected value and Variance of XX are respectively
    X=xX = x123
    P(X=x)P(X = x)1/52/52/5

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  10. Question 10

    19 May 2026 S2

    99
    The variance of randam variable XX, for the following probability mass function (p. m. f.) is ...
    X=xX = x112233
    P(X=x)P(X = x)15\dfrac{1}{5}25\dfrac{2}{5}25\dfrac{2}{5}

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