Empirical Rule Example

This worksheet may help you to know about the Empirical Rule. The data set along with Bell Shape curve will be implied to Empirical Rule. We can apply the Empirical rule if we know the value of Standard Deviation and mean. The Empirical rule for Normal Distribution is defined as 68% of values fall in 1 Standard Deviation of the mean, 95% of values are fall in 2 standard deviation of the mean and 99.73% of values are fall in 4 standard deviation of the mean.
Formula for Empirical Rule
68% of values fall => mean sd
95% of value fall => mean 2 sd
99.73% of value fall => mean 3 sd
Where,
sd- standard deviation for the given value
Mean mean for the given values

Example for Empirical Rule


Find empirical rule for the values {12,32,45,53,21,43}
Step 1: Calculate Mean
mean = (12+32+45+53+21+43)/6
mean = 206/6
mean = 34.33
Step 2: Find Standard Deviation
You can use this Standard Deviation Calculator to find Standard deviation.
SD(σ)=&radical;(1/(N-1)*((x1-xm)2+(x2-xm)2+..+(xn-xm)2))

SD(σ)=√(1/(6-1)((12-34.33)2+(32-34.33)2+(45-34.33)2+(53-34.33)2+(21-34.33)2+(43-34.33)2))
SD(σ)=√(1/5((-22.3333)2+(-2.33)2+(10.6667)2+(18.6667)2+(-13.3333)2+(8.6667)2))
SD(σ)=√(1/5((498.7763)+(5.4443)+(113.7785)+(348.4457)+(177.7769)+(75.1117)))
SD(σ)=√(243.8667)
SD(σ)=15.6162

Step 3: Apply Empirical Rule
68% of values are between 18.7171 to 49.9496
95% of Values are between 3.1009 to 65.5658
97.73% of values are between -12.5154 to 81.182

The above worksheet is an walk through to understand the concept of understanding Empirical rule. When it comes to online calculation this online Empirical Rule Calculator is an essential tool to make the calculation easy.
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