1. Perform a linear regression for the accompanying John Deere tractor horsepower versus price data.
    Images Horsepower Price
    tractor4200.jpg (4865 bytes) 26 13600
    tractor5205.jpg (4608 bytes) 48 19300
    tractor6605.jpg (8158 bytes) 95 46300
    tractor7410.jpg (6782 bytes) 105 60315
    tractor8520.jpg (4841 bytes) 255 168900
    tractor9520.jpg (4271 bytes) 450 200100
    1. Determine the slope m

    2. For the data above, determine the y-intercept

    3. Determine the correlation coefficient r =

    4. Is the correlation positive, negative, or neutral?

    5. Is the correlation none, low, moderate, high, or perfect?

    6. Determine the coefficient of determination 

    7. Based on the equation of the best fit line, what would be the predicted price for a 55 horsepower tractor?

    8. Based on the equation of the best fit line, what would be the projected horsepower of a $100,000 dollar tractor?

  2. John Deere produces tractors in the 4000 and 5000 series with the following horsepowers:

    20, 20, 32, 32, 35, 39, 40, 43, 43, 45, 45, 48, 48, 55, 55, 55, 65, 65, 65, 75, 75, 75

    1. Find the sample size n: ______

    2. Find the minimum: ______

    3. Find the maximum: ______

    4. Find the range: ______

    5. Find the median: ______

    6. Find the mode: ______

    7. Find the sample mean xbar.gif (842 bytes): ______
    8. Find the sample standard deviation sx: ______

    9. Find the sample coefficient of variation CV:______

    10. If this data is to be divided into five bins (classes, intervals) what is the width of a single bin? ________

    11. Determine the frequency and calculate the relative frequency using five bins (classes, intervals). Record your results in the table provided.
      Bins ( Classes or Intervals) Frequency Relative Frequency
      _______ _______ _______
      _______ _______ _______
      _______ _______ _______
      _______ _______ _______
      _______ _______ _______

      Sum:

      		 _______________ _______________
    12. Sketch a relative frequency histogram of the data on the back, labeling your horizontal axis and vertical axis as appropriate.

    13. What is the shape of the distribution? ______________

    14. What is the probability of a tractor having between 20 and 31 horsepower?

    15. What is the probability of a tractor having between either 20 and 31 horsepower or 32 and 42 horsepower.


Statistic or Parameter Symbol Equations Excel
Square root =SQRT(number)
Sample mean xbar.gif (842 bytes) Sx/n =AVERAGE(data)
Sample standard deviation sx =STDEV(data)
Sample Coefficient of Variation CV 100(sx/xbar.gif (842 bytes)) =100*STDEV(data)/AVERAGE(data)
Slope b =SLOPE(y data, x data)
Intercept a =INTERCEPT(y data, x data)
Correlation r =CORREL(y data, x data)
Coefficient of Determination rē =(CORREL(y data, x data))^2

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