Consider the example above.
Looking at the graph above, how much does a person earn for a day if the person worked 9 hours?
$80
$95
$100
No one line represents the function. To graph, the first piece’s line is:
0-8 hours: y = 10x
The second piece’s line starts at the first piece’s end, meaning x is 8 and y is 80. What is that line’s slope?
10
15
3)
Drawing a line with slope 15, starting at x of 8 and y of 80, can be done by drawing a second point, obtained by going 1 unit to the right and up by how many units?
1
15
95
4)
No one equation can represent the piecewise linear function. Instead, the function is described like this:
0-8 hours: y = 10x
8+ hours: y = 80 + 15(x – ?)
(The 8+ means “8 or more”).
1
8
5)
For more than 8 hours worked, the total earnings are y = 80 + 15(x – 8). A person works a long 20 hour day. How many dollars does the person earn for that long day?
$200
$260
$380
6)
Suppose the company above pays double-time (20 dollars/hour) for above 12 hours. The equations are then:
0-8 hours: y = 10x
8-12 hours: y = 80 + 15(x – 8)
12+ hours: y = ___ + 20(x – 12)
80
140
155
What is the rate per gallon for an apartment that uses under 100 gallons per day?
0.2 cents/gal
0.5 cents/gal
1 cent/gal
2)
What is the rate per gallon for an apartment that uses over 150 gallons per day?
0.2 cents/gal
0.5 cents/gal
1 cent/gal
3)
Knowing that using 150 gallons in a day costs 45 cents, and every gallon above 150 gal costs 1 cent, what would 400 gallons cost? Hint: Add the cost for those additional 400 – 150 = 250 gal to the 45 cents.
295 cents
400 cents
4)
Which equation calculates total water cost for water use between 100 and 150 gal?
y = 0.2x
y = 0.5x
y = 20 + 0.5x
y = 20 + 0.5(x – 100)
