Glencoe Pre-Algrebra

Splash Screen

Then/Now

You have already graphed ordered pairs and relations on a coordinate system. (Lesson 14)

Construct scatter plots.Analyze trends in scatter plots.Vocabulary

scatter plot

Example 1Construct a Scatter PlotBREAD The table shows the average cost of a loaf of bread from 19202000. Make a scatter plot of the data.Let the horizontal axis, or x-axis, represent the year.Let the vertical axis, or y-axis, represent the cost.

Example 1Construct a Scatter PlotBREAD The table shows the average cost of a loaf of bread from 19202000. Make a scatter plot of the data.Graph the ordered pairs (year, cost).

Answer: ABCDExample 1

BIRTH STATISTICS The table shows the number of babies born at Central Hospital during the past eight months. Make a scatter plot of the data. A.B.C.D.

ConceptExample: The hours you study and your test average have a positive relationship (as your hours go up, so do your scores)Example: The minutes a candle is burned and the height of the candle have a negative relationship (the longer you burn, the shorter the candle)Example: The number of slices of pizza you eat and your shoe size (the is no obvious relation to these two pieces of data) Example 2Interpret Scatter PlotsDetermine whether the scatter plot of the heights of basketball players and number of rebounds shows a positive, negative, or no relationship. Explain your answer. As height increases, the number of rebounds increases.Answer: positive relationship

Determine whether the scatter plot of the weight of a car and its miles per gallon shows a positive, negative, or no relationship. Explain your answer.

.1

As the weight of the car (x-value) increases the miles per gallon (y-value) decreases.Answer: negative relationshipABCDExample 2

A.As the outside temperature increases, the heating bill will decrease. This is a negative relationship.B.As the outside temperature increases, the heating bill will decrease. This is a positive relationship.C.As the outside temperature increases, the heating bill will increase. This is a negative relationship.D.Outside temperature and heating bill have no relationship.Determine whether a scatter plot of the outside temperatures and the corresponding heating bill might show a positive, negative, or no relationship. Explain your answer.

Example 3Analyze Scatter PlotsA. TEMPERATURE The table shows temperatures in degrees Celsius and the corresponding temperatures in degrees Fahrenheit. Make a scatter plot of the data.Let the horizontal axis represent degrees Celsius and the vertical axis represent degrees Fahrenheit.

Graph the data.Example 3Analyze Scatter PlotsB. Draw a conclusion about the type of relationship the data shows. Explain.Answer: A positive relationship is shown. As C increase, so do F.

Example 3Analyze Scatter PlotsC. Predict the Fahrenheit temperature for 35C.By looking at the pattern on the graph, we can predict that the Fahrenheit temperature corresponding to 35C would be about 95 degrees.

Answer: 95F

A.B.C.D.ABCDExample 3

A. STUDY SKILLS The table shows hours spent studying for a test and the corresponding test score. Make a scatter plot of the data.

ABCDExample 3

B. STUDY SKILLS The table shows hours spent studying for a test and the corresponding test score. Does the scatter plot show a relationship between hours studied and a students test score?

A.Yes, a positive relationship exists.B.Yes, a negative relationship exists.C.No, no relationship exists.D.none of the above

ABCDExample 3

C. STUDY SKILLS The table shows hours spent studying for a test and the corresponding test score. Predict the test score for a student who spends 7 hours studying.

A.between 65 and 70 B.between 75 and 80C.between 95 and 100 D.between 105 and 110

End of the Lesson