Use the fit line's equation to predict, and say what its slope and intercept mean

Answer Key - Grade 8 Math Worksheet - Building Confidence

Circle the best answer, or write your answer on the line.

1. 1.

   Milo fit a line to bike rides: length against time. The helmet is shiny and new. About how many minutes does the model predict for a 7-kilometer ride?

   25
2. 2.

   Noah's jump-rope club fit a line to weeks of practice and jumps in one minute. About how many jumps does the model predict after 7 weeks?

   75
3. 3.

   Pia's class drew a fit line on the bean plant plot. Using the line, about how tall is a plant 5 weeks after planting, in cm?

   19
4. 4.

   Ren's team drew a fit line for practice and free throws. Using the line, about how many free throws go with 7 hours of practice?

   24
5. 5.

   Tala drew a fit line through a plot of short walks. Using the line, about how many blocks go with 8 minutes of walking?

   18
6. 6.

   Zee's music club drew a fit line on its practice plot. Using the line, about how many chords go with 3 minutes of practice a day?

   18
7. 7.

   Ari's class fit the line y = 4x + 30 to practice time (x, in hours a week) and quiz scores (y). What does the 4 mean?

   • The 4 means each student practiced about 4 hours a week.
   • The 4 means every extra hour raises every student's score by exactly 4 points, with no exceptions.
   • The 4 means students who practice 1 more hour a week tend to score about 4 points higher.
   • The 4 means a student who does not practice tends to score about 4 points.
8. 8.

   Bo's garden club fit the line y = 1.5x + 4 to days outside (x) and seedling height in cm (y). What does the 1.5 mean?

   • The 1.5 means seedlings outside 1 more day tend to be about 1.5 cm taller.
   • The 1.5 means a seedling tends to be about 1.5 cm tall on its first day outside.
   • The 1.5 means every seedling grows exactly 1.5 cm each day.
   • The 1.5 means the club measured 1.5 seedlings each day.
9. 9.

   Esme fit the line y = 3x + 5 to bike rides: length in km (x) and time in minutes (y). The tires were freshly pumped. What does the 3 mean?

   • The 3 means every kilometer takes exactly 3 minutes on every ride, without any variation.
   • The 3 means rides that are 1 km longer tend to take about 3 more minutes.
   • The 3 means a ride tends to take about 3 minutes before it even starts.
   • The 3 means the rides were about 3 kilometers long.
10. 10.

    Jun's class fit the line y = 6x + 15 to shoe length (x) and height (y), both in cm. What does the 6 mean?

    • The 6 means every centimeter of shoe makes a person exactly 6 cm taller.
    • The 6 means a person tends to be about 6 cm tall with no shoes.
    • The 6 means the class measured 6 shoes.
    • The 6 means people whose shoes are 1 cm longer tend to be about 6 cm taller.