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Math Help - Set's Of numbers

  1. #1
    Junior Member Godfather's Avatar
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    Set's Of numbers

    A set of n numbers has the sum s. Eachh number of the set is increased by 20 nultipled by 5 and then decreased by 20. what is the sume of the nmber the new set in terms of s and n
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  2. #2
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    Hello, Godfather!

    I'll baby-step through this one . . .


    A set of n numbers has the sum S.
    Each number of the set is increased by 20, multipled by 5 and then decreased by 20.
    What is the sum of the numbers of the new set in terms of S and n ?

    The original set is: .a + b + c + ... + n .= .S

    Each number x is changed like this: .5(x + 20) - 20 .= .5x + 80

    The new sum is: .(5a + 80) + (5b + 80) + 5a + 80) + ... + (5n + 80)

    . . = .5(a + b + c + ... + n) + (80 + 80 + 80 + ... + 80)
    . . . . . . . . . . . . . . . . . . . . . . \__________________/
    . . . . . . . . . . . . . . . . . . . . . . . . . . . .
    n terms

    Therefore, the new sum is: .5S + 80n

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