The scatter plot at the bottom shows the amount of food eaten in a day by dogs of various masses. If the line of best fit is appropriate, explain why. If it is not appropriate, explain how you would draw an appropriate line.

The table shows the lengths of a sample of lake trout at various ages.

a. Which variable would you choose as the independent variable? Explain.

b. Are the data continuous or discrete? Explain.

c. Predict the relationship between the two variables.

d. Plot the data on a scatter plot.

e. Does the graph support your prediction? Explain.

Choose the statement that is true.

A. A line of best fit must pass through at least one or two plotted points.

B. If a line of best fit does not pass through at least two plotted points, then it is not possible to determine its slope.

C. It is sometimes possible to draw both a line of best fit and a curve of best fit to approximate plotted points.

D. A curve of best fit is more accurate than a line of best fit, since it can curve closer to the plotted points.

Grant leads a team of high school students who speak to elementary school students about the health problems that result from smoking cigarettes. Each high school student is responsible for one elementary school. Data on the number of hours spent by each high school student (in a year) and the corresponding number of smokers in each elementary school are summarized in the table.

a. Plot the data on a scatter plot.

b. Describe the pattern in the data.

c. Sketch a line or curve of best fit, whichever is more appropriate.

d. Can you conclude that the program of speaking to elementary school students has been effective in reducing smoking? Explain.

Choose the best ending for the sentence. “For a scatter plot,

A. it is always possible to draw a line of best fit.”

B. it is always possible to draw a curve of best fit.”

C. it is always possible to draw either a line of best fit or a curve of best fit.”

D. none of the choices in A., B., or C. are true.”

In the Kingdom of Petrodalla, the total length of all roads has increased over the past few decades, as has the percentage of the population that suffers from asthma. The data are summarized in the table:

a. Plot the data on a scatter plot. Use Road Length as the independent variable and the Incidence of Asthma as the dependent variable.

b. Sketch a line of best fit.

c. Determine the equation of your line of best fit.

d. Use your equation to predict the percentage incidence of asthma when the total road length is 400 km.

e. Since the percentage of asthma sufferers increases as the total length of the roads increases, Marianne concludes that roads cause asthma. Is this a valid conclusion? Explain.

Shasta runs one kilometre each day as part of her daily exercise. The graph shows her 500 distance from home as she runs her route.

a. Between what two points does Shasta run the fastest?

b. Describe what is happening between points C and D.

c. When does Shasta begin to travel toward home?

d. How long does it take her to get home?

e. How fast was she running back home?