Activity
in this activity, you will identify proportional relationships in graphs. the table gives the lengths and widths (in inches) of three different tvs.

length
(inches) width
(inches)
16 9
20 11.25
24 13.50
part a
is there a proportional relationship between the length and width of the tvs? check the table for equivalent ratios to support your answer. show your work.

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part b
think about graphing the relationship between the length and the width of the tv screens. what do you predict the graph would look like?

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part c
check your prediction in part b by graphing the relationship. use the graphing tool and follow these steps to create your graph:

press the clear button to reset the graph.
in the data window, type 0,0 to set the origin of your graph. then press enter on your keyboard to move to the next line in the window.
in the same window, enter values for length and width of each tv screen. separate the values with a comma. press enter on your keyboard to place each pair of values on its own line.
click submit to see the graph of your points.
click the line of best fit box and then click update. this passes a line through the points you created.
should you make a mistake, press update to refresh your graph or clear to start over.
you should now see a graph of the points in the relationship. when you you’re satisfied with the graph, take a screen capture of it and paste it in the answer field.

length
(inches) width
(inches)
16 9
20 11.25
24 13.50

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part d
does the graph match your prediction? how so? if your graph doesn’t match your prediction, explain why. use a straight edge to determine where your graph crosses the x- and y-axes.

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part e
this table shows the prices of the three tvs in addition to their length and width. is the price of a tv proportional to the length of its screen? how do you know?

length (inches) width (inches) price
16
9
$160
20
11.25
$180
24
13.50
$200

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part f
think about graphing the relationship between the length of the tv screen and the price. what do you predict the graph would look like?

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part g
graph the relationship between the screen length and the price using the graphing tool. before you begin, clear any previous data entries and graphs. be sure to set the origin for your graph by entering 0 for price and 0 for length for one of the points.

when you’re satisfied with your graph of price versus length, take a screen capture of it and paste it in the answer field.

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part h
does the graph match your prediction? why or why not? use a straight edge to determine where your graph crosses the x- and y-axes.

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self-evaluation
how did you do? rate your work on a scale of 1 to 5, with 5 as the highest score. then write a brief evaluation of your work below. note what you learned and what challenged you.