Statistics in a Modern World 800
Solutions to Exam 2

  1.  
    1. 5 Number Summary: 8 (1st) 10 (between 7th & 8th) 11 (14th) 12 (between 20th & 21st) 14 (last)
    2. (ii) fairly symmetric
    3. (ii) mean about equal to median
    1. (ii) bar graph is best for two categorical variables (one piechart wouldn't do; you'd need two)
    2. (iii) scatterplot displays two measurement variables
  2. (ii) correlation between IQ's and heights should be closest to 0 because we don't expect these to be related
    1. z = (294-266)/16 = 1.75; the percentage above 1.75 equals percentage below -1.75, or 4%
    2. the shortest 2% have z = -2.05; observed value = 266 -2.05(16)=233.2
  3.  
    1. predicted shoesize = -13 + .322(62) = 7
    2. direction is (i) positive because .322 > 0; anyway, taller heights are associated with longer feet.
  4. take 100 billion times 175 divided by 35: answer is 500 billion
    1. (i) long-term trend (decrease) is most pronounced
    2. (iv) irregular cycle of increase then decrease from '91 to '95
    1. 5 is answered for you
    2. 2
    3. 1
    4. 6
    5. 4
    6. 7
    7. 3
    1. first column 10 and 10; second column 20 and 20
    2. first column 4.9 and 4.9; second column 2.5 and 2.5
    3. chi-square is 14.8
    4. yes: 14.8 > 3.84 means we have statistical evidence of a relationship
    5. (ii) in general, upperclassmen tend to live off campus


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