Extra Set

Grade 8 · Unit 7 · L30 · Version A · 3ABD

Equation of a linear model

Name ________________

Date ________________

Period ________________

1.
A trend line is y = 3x + 3. Predict y when x = 6.
Answer. 21
y = 3(6) + 3 = 21.
2.
A trend line is y = 4x + 8. Predict y when x = 6.
Answer. 32
y = 4(6) + 8 = 32.
3.
A trend line is y = 3x + 9. Predict y when x = 4.
Answer. 21
y = 3(4) + 9 = 21.
4.
A trend line is y = 3x + 2. Predict y when x = 10.
Answer. 32
y = 3(10) + 2 = 32.
5.
A trend line is y = 2x + 8. Predict y when x = 8. Then Theo needs 2 of that amount. What is the total they need?
Answer. 48
y = 2(8) + 8 = 24. Then multiply by 2: 48.
6.
A trend line is y = 5x + 3. Predict y when x = 8. Then Sam needs 2 of that amount. What is the total they need?
Answer. 86
y = 5(8) + 3 = 43. Then multiply by 2: 86.
7.
A trend line is y = 6x + 2. Predict y when x = 4. Then Priya needs 4 of that amount. What is the total they need?
Answer. 104
y = 6(4) + 2 = 26. Then multiply by 4: 104.
8.
A trend line is y = 5x + 1. Predict y when x = 7. Then Nora needs 5 of that amount. What is the total they need?
Answer. 180
y = 5(7) + 1 = 36. Then multiply by 5: 180.
9.
A trend line is y = 5x + 4. Predict y when x = 6. Then Grace needs 4 of that amount. What is the total they need?
Answer. 136
y = 5(6) + 4 = 34. Then multiply by 4: 136.
10.
A trend line is y = 6x + 1. Predict y when x = 4. Then Nora needs 4 of that amount. What is the total they need?
Answer. 100
y = 6(4) + 1 = 25. Then multiply by 4: 100.
11.
Think
Sam tried this problem:
A trend line is y = 4x + 10. Predict y when x = 4.
Sam wrote 25. That is not correct. What is the right answer?
Answer. 26
Sam’s answer 25 is off. y = 4(4) + 10 = 26.
12.
Think
Ava tried this problem:
A trend line is y = 3x + 3. Predict y when x = 10.
Ava wrote 32. That is not correct. What is the right answer?
Answer. 33
Ava’s answer 32 is off. y = 3(10) + 3 = 33.

Original extra practice. Keys are computed from the items, not guessed.

L30 · Equation of a linear model