Scatterplots and Trend Lines

The scatterplot shows the relationship between the length of a long-distance phone call and the cost of the phone call.

Based on the line of best fit for the scatterplot, which of the following amounts is closest to the cost of a 120 minute phone call?

• $10

• $12

• $15

• $20

The scatterplot shows the average traffic volume and average vehicle speed on a certain freeway for 50 days in 1999. Which statement best describes the relationship between average traffic volume and average vehicle speed shown on the scatter plot?

• As traffic volume increases, vehicle speed increases at first, then decreases.

• As traffic volume increases, vehicle speed decreases at first, then increases.

• As traffic volume increases, vehicle speed decreases.

• As traffic volume increases, vehicle speed increases.

The police department tracked the number of ticket writers and number of tickets issued for the past 8 weeks. The scatterplot shows the results. Based on the scatter plot, which statement is true?

• There were 50 tickets issued every week.

• More ticket writers results in fewer tickets issued.

• More ticket writers results in more tickets issued.

• When there are 10 ticket writers, there will be 800 tickets issued.

Mr. Thomas wanted to know if the amount of class time that he gave students to study affected their test scores. The scatterplot shows the results. What kind of relationship between class study time and test scores is shown on the scatter plot?

• No correlation

• Positive then negative correlation

• Positive correlation

• Negative correlation

The following scatterplot shows the weights and lengths of some dinosaurs. Which statement accurately describes the information in the scatter plot?

• The information shows a positive correlation. The weight of a dinosaur tends to increase according to its length.

• The information shows a negative correlation. The weight of a dinosaur tends to decrease according to its length.

• The information shows no correlation. The weight and length vary according to the type of dinosaur.

• The information shows no correlation. The relationship between the weight and length of a dinosaur is uncertain.

Which data will most likely show a negative correlation when graphed on a scatterplot?

• The outside temperature and the number of people wearing gloves

• A student's height and grade point average

• The distance a student lives from school and the amount of time it takes to get to school

• The number of visitors at an amusement park and the length of the lines for the rides

This scatterplot could show the relationship between which two variables?

• speed of an airplane (x) vs. distance traveled (y)

• outside air temperature (x) vs. air conditioning costs (y)

• age of an adult (x) vs. height of an adult (y)

• distance traveled (x) vs. gas remaining in the tank (y)

Which graph shows a line of best fit for the scatterplot?

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For which scatterplot would the line of best fit be represented by the equation:

y=1/2 x +2?

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A researcher gathered data to predict the number of new types of plants (y) that will be in a state park after x years. After making a scatterplot of the data, she determined the equation of a line of best fit. The equation is shown below.

y = 0.25x+8

Based on the equation, what is the number of new types of plants that will be in the park after 24 years?

• 8

• 14

• 32

• 64