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    Mean comparison

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    I have a poor understanding of this subject. Please assist me with the attachment and explain your steps so that I can try to understand this area. Please use the traditional method becasue I can follow it a little better. Thank you for your help.

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    https://brainmass.com/statistics/hypothesis-testing/mean-comparison-different-scales-18280

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    2.)
    For test#1:
    mean = 100; sd = 25; score = 130
    Hence,
    (score-mean)/sd = (130-100)/25 = 30/25 = 6/5 = 1.2

    For test#2:
    mean = 40; sd = 5; score = 52
    Hence,
    (score-mean)/sd = (52-40)/5 = 12/5 = 2.4 > 1.2

    Because, in 1st case score is closer to the mean in comparison to second score, therfore 130 on test#1 is better score --Answer (A)

    3.)
    Sample space ={(BBB), (GBB), (BBG), (BGB), (BGG), (GBG), (GGB), (GGG)}
    where G stand for girl and B stands for boy.

    Hence, sample size = 8 --Answer

    Probability of at least two girls P= n(2 girls or 3 girls)/n(total)
    2 or 3 girls = {(BGG), (GBG), (GGB), (GGG)}

    => P = 4/8 = 1/2 --Answer (B)

    4.)
    P(Aisle or smoking)
    = [n(Aisle) + n(smoking) - n(aisle and smoking)]/n(total)

    n(aisle) = 15 + 80 = 95
    n(smoking) = 30
    n(smoking and aisle) = 15
    n(total) = 230
    Hence,
    P(Aisle or smoking) = (95 + 30 - 15)/230

    => P = 0.478 --Answer (D)

    5.)
    probability of a eligible voter to vote = p = 48/100 = 0.48

    Hence, probability that all 4 eligible voters vote
    P = p^4 = (0.48)^4

    => P = 0.0531 --Answer (A)

    6.)
    Number of possible exams each comprised of 10 questions out of 20
    n = 20C10 = 20!/(10!*10!)
    => n = 20*19*18*17*16*15*14*13*12*11/(10*9*8*7*6*5*4*3*2*1)

    => n = 184756 --Answer

    7.)
    Let us take class size = ...

    Solution Summary

    Two tests were given, the tests were designed with different scales. The solution discusses the mean comparison.

    $2.19

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