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    mean x=25, n=100
    Find Σ(x-20)

    ANS: 500
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    Well. You can work out what all the x added up to and then imagine what would happen if 20 was taken off every one.

    I assume you are asking where the answer came from?
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    (Original post by rollsroyce_tan)
    mean x=25, n=100
    Find Σ(x-20)

    ANS: 500
    It's because \dfrac{\sum x}{n}= \overline{x} \Rightarrow \overline{x} n=\sum x so you have \displaystyle \sum_{i=1}^{100} (x_i-20) = \sum_{i=1}^{100} x_i - \sum_{i=1}^{100} 20
 
 
 
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