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Question

Which one of the following is standard deviation of first 7 (1 to 7) natural numbers?

The correct answer is
2

Standard Deviation Calculation for First 7 Natural Numbers

The question asks for the standard deviation of the first 7 natural numbers, which are 1, 2, 3, 4, 5, 6, 7.

Step 1: Calculate the Mean

The mean ($\mu$) is the average of the numbers.

Numbers = {1, 2, 3, 4, 5, 6, 7}

Number of observations (N) = 7

Mean ($\mu$) = $\frac{1+2+3+4+5+6+7}{7} = \frac{28}{7} = 4$

Step 2: Calculate the Variance

Variance ($\sigma^2$) is the average of the squared differences from the Mean.

  • Squared difference for 1: $(1 - 4)^2 = (-3)^2 = 9$
  • Squared difference for 2: $(2 - 4)^2 = (-2)^2 = 4$
  • Squared difference for 3: $(3 - 4)^2 = (-1)^2 = 1$
  • Squared difference for 4: $(4 - 4)^2 = (0)^2 = 0$
  • Squared difference for 5: $(5 - 4)^2 = (1)^2 = 1$
  • Squared difference for 6: $(6 - 4)^2 = (2)^2 = 4$
  • Squared difference for 7: $(7 - 4)^2 = (3)^2 = 9$

Sum of squared differences = $9 + 4 + 1 + 0 + 1 + 4 + 9 = 28$

Variance ($\sigma^2$) = $\frac{\text{Sum of squared differences}}{N} = \frac{28}{7} = 4$

Step 3: Calculate the Standard Deviation

The standard deviation ($\sigma$) is the square root of the variance.

Standard Deviation ($\sigma$) = $\sqrt{\text{Variance}} = \sqrt{4} = 2$

Therefore, the standard deviation of the first 7 natural numbers is 2.

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Important Questions from Measures of Dispersion - Teaching

  1. If the probability of winning a match is 0.7, then what is the value of variance ?

  2. _____ is a measure of dispersion that considers all the scores
  3. The $90^{th}$ percentile value for the data : 6, 6, 6.5, 7.0, 7.5, 6.5, 6, 7.5 and 8 is :
  4. Which one is the correct formula for variance ?
  5. Match items of List - I with that of List - II and select the correct option using the codes given below :

    List – IList – II
    (a)Coefficient of variation(i)Square root of the average of the squared deviation measured from mean.
    (b)Standard deviation(ii)Absolute measure of dispersion around median.
    (c)Mean deviation(iii)Variation of the distribution adjusted with mean in percentage.
    (d)Quartile deviation(iv)Average of the absolute deviation of scores from a measure of central tendency.
      (v)Under root of the squared value of maximum variance from mean.

    Codes :

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