Unit D: Graphing

Practice


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  1. The following scatterplot shows the resting heart rates (in beats per minute) for various 30-year-old males compared to the hours of exercise they get per week. The line of best fit has been drawn.




    1. Describe the trend between the hours of exercise and the resting heart rate of 30-year-old males.

    2. If a 30-year-old male exercises 2 hours per week, what is his resting heart rate?

    3. If a 30-year-old male has a resting heart rate of 65 beats per minute, approximately how many hours would he exercise per week?

  2. Lee receives a base salary plus paid commission on his sales at a computer store. The equation that represents his salary is y = 0.05x + 100, where x is the computer product sales in dollars and y is Lee's earnings in dollars.

    1. Does the equation represent direct variation or partial variation?

    2. What does the slope of the line represent?

    3. What does the y-intercept represent?

    4. How much will Lee earn if he sells computer products worth $1 000?

    5. Set up a table of values to draw the graph of Lee's earnings. Include the values of $1 000, $2 000, $3 000, and $4 000 in sales when calculating Lee's earnings. Use the equation y = 0.05x + 100.

    6. Use the graph to determine how much Lee needs to sell to earn $400.

  3. Ohm's law is an important direct variation relationship between current and voltage. The scatterplot for voltage compared to current is displayed below.




    1. State if the scatterplot shows positive correlation, negative correlation, or no correlation.

    2. What trend is seen in the scatterplot?

    3. Draw the line of best fit.

    4. What is the voltage when the current is 13 amps?

    5. What is the current when the voltage is 2.0 volts?
The following scatterplot shows the resting heart rates (in beats per minute) for various 30-year-old males compared to the hours of exercise they get per week. The line of best fit has been drawn.




  1. Describe the trend between the hours of exercise and the resting heart rate of 30-year-old males.

  2. If a 30-year-old male exercises 2 hours per week, what is his resting heart rate?

  3. If a 30-year-old male has a resting heart rate of 65 beats per minute, approximately how many hours would he exercise per week?

  1. As the hours of exercise increase, the resting heart rates of 30-year-old males decrease.




  2. Using the method of interpolation, a 30-year-old male who exercises 2 hours per week would have a resting heart rate of approximately 72 bests per minute.




  3. A 30-year-old male who has a resting heart rate of 65 beats per minute exercises approximately 3.75 hours per week.
Lee receives a base salary plus paid commission on his sales at a computer store. The equation that represents his salary is y = 0.05x + 100, where x is the computer product sales in dollars and y is Lee's earnings in dollars.

  1. Does the equation represent direct variation or partial variation?

  2. What does the slope of the line represent?

  3. What does the y-intercept represent?

  4. How much will Lee earn if he sells computer products worth $1 000?

  5. Set up a table of values to draw the graph of Lee's earnings. Include the values of $1 000, $2 000, $3 000, and $4 000 in sales when calculating Lee's earnings. Use the equation y = 0.05x + 100.

  6. Use the graph to determine how much Lee needs to sell to earn $400.

  1. Since the equation is in the form y = mx + b, the equation represents partial variation, where the slope is 0.05 and the y-intercept is 100.

  2. The slope of 0.05 represents the 5% commission that Lee earns on computer product sales.

  3. The y-intercept represents Lee's base salary of $100 per day.

  4. y = 0 . 05 x + 100 y = 0 . 05 1   000 + 100 = 50 + 100 = 150

    Lee will earn $150 if he sells computer products worth $1 000.

  5. Sales ($)
    		Earnings ($)
    1 000
    		150
    2 000
    		200
    3 000
    		250
    4 000
    		300







  6. This value is determined using extrapolation. Lee needs to sell $6 000 in computer products to earn $400.
Ohm's law is an important direct variation relationship between current and voltage. The scatterplot for voltage compared to current is displayed below.




  1. State if the scatterplot shows positive correlation, negative correlation, or no correlation.

  2. What trend is seen in the scatterplot?

  3. Draw the line of best fit.

  4. What is the voltage when the current is 13 amps?

  5. What is the current when the voltage is 2.0 volts?

  1. The graph shows positive correlation.

  2. As the current increases, the voltage increases.







  4. Using extrapolation, the voltage is approximately 2.8 volts when the current is 13 amps.




  5. Using interpolation, the current is approximately 9.2 amps when the voltage is 2.0 volts.