The mean of the set of numbers 2,3,(k+1),(k+3) and 17 is (k+l). calculate the standard deviation

Mathematics

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Answer

5.4037

Step-by-step solution

5 steps
  1. Calculate the value of kk.

    The set of numbers is 2,3,(k+1),(k+3),172, 3, (k+1), (k+3), 17. There are 5 numbers.
    The mean of these numbers is (k+1)(k+1).
    The formula for the mean is Mean=∑xN\text{Mean} = \frac{\sum x}{N}.

    k+1=2+3+(k+1)+(k+3)+175k+1 = \frac{2+3+(k+1)+(k+3)+17}{5} k+1=26+2k5k+1 = \frac{26+2k}{5}

    Multiply both sides by 5:

    5(k+1)=26+2k5(k+1) = 26+2k 5k+5=26+2k5k+5 = 26+2k

    Subtract 2k2k from both sides:

    3k+5=263k+5 = 26

    Subtract 5 from both sides:

    3k=213k = 21 k=213k = \frac{21}{3} k=7k = 7
  2. Determine the actual set of numbers and their mean.

    Substitute k=7k=7 into the expressions:
    k+1=7+1=8k+1 = 7+1 = 8
    k+3=7+3=10k+3 = 7+3 = 10
    The set of numbers is 2,3,8,10,172, 3, 8, 10, 17.
    The mean of the set is k+1=7+1=8k+1 = 7+1 = 8.

  3. Calculate the squared differences from the mean (xi−μ)2(x_i - \mu)^2.

    The mean μ=8\mu = 8.
    For x1=2x_1 = 2: (2−8)2=(−6)2=36(2-8)^2 = (-6)^2 = 36
    For x2=3x_2 = 3: (3−8)2=(−5)2=25(3-8)^2 = (-5)^2 = 25
    For x3=8x_3 = 8: (8−8)2=(0)2=0(8-8)^2 = (0)^2 = 0
    For x4=10x_4 = 10: (10−8)2=(2)2=4(10-8)^2 = (2)^2 = 4
    For x5=17x_5 = 17: (17−8)2=(9)2=81(17-8)^2 = (9)^2 = 81

  4. Sum the squared differences.

    ∑(xi−μ)2=36+25+0+4+81=146\sum (x_i - \mu)^2 = 36 + 25 + 0 + 4 + 81 = 146
  5. Calculate the standard deviation.

    The formula for the population standard deviation (σ\sigma) is σ=∑(xi−μ)2N\sigma = \sqrt{\frac{\sum (x_i - \mu)^2}{N}}.
    Here, N=5N=5 (the number of values).

    σ=1465\sigma = \sqrt{\frac{146}{5}} σ=29.2\sigma = \sqrt{29.2} σ≈5.4037\sigma \approx 5.4037

    The standard deviation is 5.4037.

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