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An Introduction to Statistics

Odd Solutions for Statistics HW Lesson 4

  1. (8 points) The population of 58 in the class of 2004, 8th grade, Algebra Diagnostic Test scores were stratified into groups of 6 taken from the data set in descending order. Using a die, one from each strata was randomly selected to obtain the following results presented in random order:
    61, 101, 46, 97, 75, 112, 63, 56, 106

    Find the sample size, sum of the data, mean, mode, median, and midrange.
    n=9   sum=717   mean=79.7   no mode   med=75   mr=79

  2.  

  3. Compare the average results obtained in the problems above with those provided for the full population (or did you lose your answer key?).
    µ=69.2   mode=56   med=68   mr=(140+28)/84=?(was in error)
  4.  

  5. What would you expect each of these average values to be, if say a million or billion digits of e were used?
    mean=4.5   no mode   med=4.5   mr=4.5
  6.  

  7. Four students drive from Michigan to Florida (2000 km) at 100.0 kph and return at 80.0 kph. Find the average round trip speed, using the harmonic mean.
    2/(1/100 + 1/80) = 88.9 kph
  8.  

  9. Tom Foolery measures the dc voltage in a standard outlet as 120 volts, -160 volts, 95 volts, and 10 volts at random intervals. Help him calculate the RMS voltage.
    (120)2 + (-160)2 + 952 + 102 = 49125; now divide by n=4 and take the square root. 110.8
  10.  

  11. Using the inauguration ages from the previous homework, calculate the 10% trimmed mean and 20% trimmed mean.
    A. Trim 4 scores off both the low and the high end.
    10% trimmed mean = 54.7 (for 36 scores);
    20% trimmed mean = 54.6 (for 26 scores)
  12.  

  13. Examine lesson 13.4 in your Geometry textbook and do problems 2-3.
    1.  

    2. Find the geometric mean of 9 and 12 to the nearest hundredth.
      10.39

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