How to find mode and median of a frequency distribution?
Question:
Find the mode and median of a frequency distribution when Mean = 40, Variance = 625 and Pearsonian's Coefficient of Skewness (Sₖₚ) = -0.2
Solution:
Step 1: Not the given data.
Sₖₚ = -0.2
Mean = 40
Variance = 625
Step 2: Find Standard deviation from Variance
Standard Deviation = √Variance
∴ Standard Deviation = √624
∴ Standard Deviation = 625
Step 3: Find Mode using Karl Pearson's Coefficient of Skweness's formula
Sₖₚ = [Mean - Mode] / Standard Deviation
∴ -0.2 = [40 - Mode] / 25
∴ -0.2 x 25 = 40 - Mode
∴ -5 = 50 - Mode
∴ Mode = 40 + 5
∴ Mode = 45
Step 4: Find Median using Karl Pearson's Coefficient of Skeweness's formula
Sₖₚ = 3 x [Mean - Median] / Standard Deviation
∴ -0.2 = 3 x [40 - Median] / 25
∴ -5 = 120 - 3 x Median
∴ 3 x Median = 125
∴ Median = 125 / 3
∴ Median = 41.67
Answer:
Mode = 45 and Median = 41.67 when Karl Pearson's Coefficient of Skweness = -0.2, Mean = 40 and Variance = 625.
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