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statistics

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In a population of exam scores,a score of X= 48 corresponds to z= 1 and a score of X= 36 corresponds to z= -.50. Find the mean and standard deviation for the population?

  • statistics - ,

    z-score = (x-mean)/sd

    1 = (48-m)/s
    s = 48-m
    s+m = 48 , #1

    -1/2 = (36-m)/s
    (-1/2)s = 36-m
    -s = 72 - 2m
    2m - s = 72 , #2

    add #1 and #2
    3m = 120
    m = 40

    then s+40 = 48
    s = 8

    mean = 40 , SD = 8

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