1. Scatter Plots and Equations of Lines
ALGEBRA 1 LESSON 6-6
12. a.
b. Answers may vary y = 3.25x – 1
c. Answers may vary.
Sample: The slope is the approximate ratio of the circumference to the diameter.
d. 14 cm
13. a.
b. Answers may vary.
Sample: y = 0.939x + 13,800
c. 143,800,000
d. Answers may vary.
Sample: No, the year
is too far in the future.
14. a. Check students’ work.
b. 1
15. Answers may vary.
Sample: pos. slope; as
temp. increases, more
students are absent.
16. a. y = 0.61x
Sample: small set of
data with weak
correlation
17. y = 0.37x – 28.66; $12.04 billion
6-6

2. Scatter Plots and Equations of Lines
ALGEBRA 1 LESSON 6-6
18. a. y = –16.70x
b. –
c. No, the correlation
coefficient is not close
to 1 or –1, so the
equation does not
closely model the
data.
19. a. (2, 3) and (6, 6);
y = 0.75x + 1.5
b. y = 0.75x
20. a.
y = 4.82x – 29.65
b. 404 ft
c. The speed is much faster
than those speeds used to find
the equation of a trend line.
21. B
22. H
23. [4] a.
b–c. Answers may vary.
Samples:
b. Let 1960 = 60. Two points
on line are (62, 18) and (90, 30).
y = 0.429x – 8.6
c. y = 0.429(105) – 8.6; 36.4 million people
6-6

3. Scatter Plots and Equations of Lines
ALGEBRA 1 LESSON 6-6
[3] appropriate methods but one
computational error
[2] incorrect points used correctly OR
correct points used incorrectly;
function written appropriately,
given previous results.
[1] correct function, without work shown
24. y + 3 = 5(x – 2)
25. y – 5 = –x
26. y – 4 = – (x + 1)
27. y + 4 = – (x – 3)
28. y + 1 = –2(x + 2)
29. y – 2 = (x + 1)
30. x > 1
31. x < 5
32. x > –1
33. x –5
34. x >
35. x < 3 2 3 1 4
< –
6-6