Build a linear or exponential model, and say what the numbers mean

Answer Key - Grade 9 Math Worksheet - Building Confidence

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

1. 1.

   Bo's bean plant is 20 cm tall at week 0. In the growth table, every arrow is + 3 cm. What model gives y after x weeks?

   y = 3x + 20
2. 2.

   Esme's art club has 8 posters at week 0. In the growth table, every arrow is + 6 posters. What model gives y after x weeks?

   y = 6x + 8
3. 3.

   A science video shows 200 yeast cells at hour 0. In Jun's growth table, every arrow is × 1.5. What model gives y after x hours?

   y = 200(1.5)^x
4. 4.

   Luz's flower-count model is exponential. The growth table has 20 at x = 0 and 50 at x = 1. What is the factor b on each arrow?

   2.5
5. 5.

   Milo's food-drive box model is linear. The growth table has 30 at x = 0 and 42 at x = 1. What is the rate m on each arrow?

   12
6. 6.

   Noah's bus-club member model is exponential. The growth table has 80 at x = 0 and 100 at x = 1. What is the factor b on each arrow?

   1.25
7. 7.

   Pia's reading-log page model is linear. The growth table has 64 at x = 0 and 80 at x = 1. What is the rate m on each arrow?

   16
8. 8.

   Ren's class tracks its trip fund with y = 12x + 40, in dollars after x weeks. What does the 12 mean?

   • The fund starts with $12
   • $12 is added each week
   • The fund has $12 after 12 weeks
9. 9.

   Tala models the juice left in a jug with y = 250 − 15x, in mL after x minutes. What does the 250 mean?

   • There are 250 mL after 15 minutes
   • There are 250 mL at the start
   • 250 mL are poured out each minute
10. 10.

    A chess club's members follow y = 120(1.06)^x after x months. Zee asks: what does the 1.06 mean?

    • Members grow by 106% each month
    • Members grow by 6% each month
    • The club gains 1.06 members each month