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And obviously the new mean is 1.2 times the old mean because we're multiplying
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everything up by 20% raise that makes a factor of 1.2 over here and zero over here
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because we don't really add a constant amount of money per person its variable.
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It's a multiplicative change. For the variance it's more interesting.
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In our new variance, we multiply each salary by a factor of 1.2 and the same is through for the mean.
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When we look at this, we can bring the 1.2 outside these brackets and it becomes (1.2)².
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The reason why I squared this, we can bring it outside Xi and u but there's a square over here
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and we can move it outside this sum as a factor.
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Now this is true for the variance but not the standard deviation.
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The standard deviation is cleared of the variance.
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The standard deviation was up by factor of 1.2 only, with a constant offset of zero.