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The next two questions refer to the following data: The cost of a leading liquid laundry detergent in different sizes is given below.

Size (ounces) Cost ($) Cost per ounce
16 3.99
32 4.99
64 5.99
200 10.99
  • Using “size” as the independent variable and “cost” as the dependent variable, make a scatter plot.
  • Does it appear from inspection that there is a relationship between the variables? Why or why not?
  • Calculate the least squares line. Put the equation in the form of: y ^ = a + bx size 12{y=a+ ital "bx"} {}
  • Find the correlation coefficient. Is it significant?
  • If the laundry detergent were sold in a 40 ounce size, find the estimated cost.
  • If the laundry detergent were sold in a 90 ounce size, find the estimated cost.
  • Use the two points in (e) and (f) to plot the least squares line on your graph from (a).
  • Does it appear that a line is the best way to fit the data? Why or why not?
  • Are there any outliers in the above data?
  • Is the least squares line valid for predicting what a 300 ounce size of the laundry detergent would cost? Why or why not?
  • What is the slope of the least squares (best-fit) line? Interpret the slope.
  • Yes
  • y ^ = 3 . 5984 + 0 . 0371 x size 12{y=3 "." "5984"+0 "." "0371"x} {}
  • 0.9986; Yes
  • $5.08
  • $6.93
  • No
  • Not valid
  • slope = 0.0371. As the number of ounces increases by one, the cost of liquid detergent tends to increase by $0.0371 or is predicted to increase by $0.0371 (about 4 cents).
  • Complete the above table for the cost per ounce of the different sizes.
  • Using “Size” as the independent variable and “Cost per ounce” as the dependent variable, make a scatter plot of the data.
  • Does it appear from inspection that there is a relationship between the variables? Why or why not?
  • Calculate the least squares line. Put the equation in the form of: y ^ = a + bx size 12{y=a+ ital "bx"} {}
  • Find the correlation coefficient. Is it significant?
  • If the laundry detergent were sold in a 40 ounce size, find the estimated cost per ounce.
  • If the laundry detergent were sold in a 90 ounce size, find the estimated cost per ounce.
  • Use the two points in (f) and (g) to plot the least squares line on your graph from (b).
  • Does it appear that a line is the best way to fit the data? Why or why not?
  • Are there any outliers in the above data?
  • Is the least squares line valid for predicting what a 300 ounce size of the laundry detergent would cost per ounce? Why or why not?
  • What is the slope of the least squares (best-fit) line? Interpret the slope.

According to flyer by a Prudential Insurance Company representative, the costs of approximate probate fees and taxes for selected net taxable estates are as follows:

Net Taxable Estate ($) Approximate Probate Fees and Taxes ($)
600,000 30,000
750,000 92,500
1,000,000 203,000
1,500,000 438,000
2,000,000 688,000
2,500,000 1,037,000
3,000,000 1,350,000

  • Decide which variable should be the independent variable and which should be the dependent variable.
  • Make a scatter plot of the data.
  • Does it appear from inspection that there is a relationship between the variables? Why or why not?
  • Calculate the least squares line. Put the equation in the form of: y ^ = a + bx size 12{y=a+ ital "bx"} {}
  • Find the correlation coefficient. Is it significant?
  • Find the estimated total cost for a net taxable estate of $1,000,000. Find the cost for $2,500,000.
  • Use the two points in (f) to plot the least squares line on your graph from (b).
  • Does it appear that a line is the best way to fit the data? Why or why not?
  • Are there any outliers in the above data?
  • Based on the above, what would be the probate fees and taxes for an estate that does not have any assets?
  • What is the slope of the least squares (best-fit) line? Interpret the slope.
  • Yes
  • y ^ = 337 , 424 . 6478 + 0 . 5463 x size 12{y= - "337","424" "." "6478"+0 "." "5463"x} {}
  • 0.9964; Yes
  • $208,875.35; $1,028,325.35
  • Yes
  • No
  • slope = 0.5463. As the net taxable estate increases by one dollar, the approximate probate fees and taxes tend to increase by 0.5463 dollars (about 55 cents).

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Source:  OpenStax, Collaborative statistics using spreadsheets. OpenStax CNX. Jan 05, 2016 Download for free at http://legacy.cnx.org/content/col11521/1.23
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