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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. From the following identify the measures of dispersion
    A. Mean Deviation
    B. Range
    C. Standard Deviation
    D. Coefficient of Variation
    E. Coefficient of Correlation
    Choose the correct answer from the options given below:
  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. _____ is a measure of dispersion that considers all the scores
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