Linear Relations
1. Let's analyze the hiker altitude problem first.
The table shows hours hiked ($x$) vs altitude ($y$).
Points: (1, 5650), (2, 5525), (3, 5400), (5, 5150), (8, 4775).
2. Calculate the rate of change (slope) $$m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{5525 - 5650}{2 - 1} = \frac{-125}{1} = -125.$$ This means altitude decreases by 125 ft each hour.
3. Using point-slope form with point (1, 5650): $$y - 5650 = -125(x - 1) \implies y = -125x + 125 + 5650 = -125x + 5775.$$
4. Now check the students' equations:
- Mateo: $y = 125x + 5775$ (wrong slope, should be negative)
- Julie: $y = -125x + 5775$ (correct)
- Oliver: $y = -125x + 5650$ (wrong intercept)
So, Julie wrote the correct equation.
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5. Now for the reading problem:
Table shows hours read ($x$) vs pages remaining ($y$).
Points: (1, 644), (4, 500), (8, 308), (12, 116), (14, 20).
6. Calculate rate (pages per hour):
Between (1, 644) and (4, 500): $$m = \frac{500 - 644}{4 - 1} = \frac{-144}{3} = -48.$$ The student reads at 48 pages per hour. Statement 9: True.
7. To find total pages, find intercept when $x=0$:
Use $y = mx + b$, with $m = -48$, and point (1, 644):
$$644 = -48(1) + b \implies b = 644 + 48 = 692.$$
So, total pages = 692. Statement 10: False (number given 644), correct statement: "Number of pages in the novel is 692."
8. Given $y = -48x + 692$, check if it fits data.
At $x=1$: $y = -48(1) + 692 = 644$ matches table.
So statement 11: True.
Final answers:
- 8. Correct equation by Julie: $y = -125x + 5775$
- 9. True
- 10. False, correct total pages 692
- 11. True