Compare two relationships shown in different ways

Answer Key - Grade 8 Math Worksheet - Challenge Me

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

1. 1.

   B (rule): y = 2.5x + 1. Ari compares two plants, A and B. A's table has uneven steps. Which plant grows faster?

   • A grows faster: its table reaches 15 cm
   • A grows faster: it jumps 6 cm, more than 2.5
   • A grows faster: it starts higher, at 3 cm
   • B grows faster: 2.5 cm a week, more than 2

2. Read this first

   A (rule): y = -2x + 8. B

   table, x	y
   0	20
   1	15
   2	10

3. 2.

   In math club, Esme compares two falling lines, A and B. Which line has the greater rate of change?

   • B is greater: 5 is more than 2
   • A is greater: -2 is greater than -5
   • B is greater: it starts higher, at 20
4. 3.

   A (story): a bottle holds 600 mL and loses 150 mL each hour. On a hike, Jun tracks two water bottles, A and B. Which has the greater rate of change, in mL per hour?

   • B is greater: it starts higher, at 900 mL
   • B is greater: 200 is more than 150
   • A is greater: -150 is greater than -200
5. 4.

   In math club, Kira compares two lines, A and B, with no row for x = 0. Which line starts higher (at x = 0)?

   • A starts higher: it changes 2 each step
   • A starts higher: its first row shows -1
   • B starts higher: -1 at x = 0, more than -7

6. A (rule): y = -3x + 5. B

   table, x	y
   2	6
   4	4
   6	2

7. 5.

   In math club, Luz compares two falling lines, A and B. Which line starts higher (at x = 0)?

   • B starts higher: 8 at x = 0, more than 5
   • A starts higher: it changes 3 each step, more than 1
   • They start equally high: both fall

8. A (story)

   a plant is 9 cm at week 2 and 17 cm at week 6. B (rule): y = 0.5x + 6.5.

9. 6.

   Milo compares two steady plants, A and B. Which plant started taller (at week 0)?

   • B started taller: 6.5 cm at week 0, more than 5
   • A started taller: it grows 2 cm a week
   • A started taller: it is 9 cm at week 2
10. 7.

    B (story): 3 cm of wax has melted, and 0.5 cm more melts each hour. Pia compares A and B. How much faster does candle A melt than candle B, in cm per hour?

    1.5

11. A (rule): y = 3x + 2. B

    table, weeks	cm
    0	8
    1	9
    3	11

12. 8.

    Tala compares A and B. After 5 weeks, how many cm taller is plant A than plant B?

    4
13. 9.

    Zee compares A and B. After 7 seconds, how many more meters of string has kite A let out than kite B?

    8

14. A (story): a 30 cm candle burns 4 cm each hour. B

    table, hours	cm
    0	25
    3	22
    6	19

15. 10.

    Ari compares A and B. After 1 hour, how many cm taller is candle A than candle B?

    2