Algebra 1 REVIEW ANSWER KEY!!!
Unit 3: Mini-Test #3
1. Melissa wants to start a donation committee for the holiday season. She starts by donating $30 and hopes to gain
$100 in donations per month from her family and people at school.
a. Complete the table of values to show how much money Melissa will have collected in 5 months.
X Y
0 30
1 130
2 230
3 330
4 430
5 530
b. What is the rate of change (slope) of Melissa’s donations?__________100 dollars PER month________
2. Michael bought a new X-Box Video Game System and can purchase video games for an additional cost per game. The
total cost of Michael’s X-Box system and the number of video games purchased is graphed below.
Michael’s X-Box Costs
a. How much did Michael pay for the X-Box?
Michael paid $150 for the X-box. I know this because it is the y-intercept!
b. What is the slope of the line? Pick two points (any two points on the
line). Use the formula (y2-y1)/ (x2-x1)
(0, 150) and (3, 300) 300-150 150/3 = 50
3–0
c. What does the slope represent in this problem? $50 per game (rate of
change
3. Find the slope of the line that goes through the points (3,6) and (5,-4) Show your work with a table of values, slope
triangle, or the slope formula…your choice!
-4 – 6 - 10 -5
5–3 2
4. BIG CATS: The table shows the approximate home range size of big cats (members of the Panthera genus) in their
natural habitat and the percent of time that the cats spend pacing in captivity.
Big Cat Lion Jaguar Leopard Tiger
Home range size 148 90 34 48
Pacing (percent of time) 48 21 11 16
a. Write the equation that best describes this data.
To find an line of best fit…use your calculator! Here are the steps…
Step one: Enter the data into your lists:
Stat Edit
Clear L1 and L2
Enter Data
Step two: Graph the data (the scatter plot):
Make sure your plots are on (Y = OR 2nd Y =)
Zoom 9 (this will give you a window that shows your statistical data
Step three: Find the line of best fit
Stat CALC (which means calculate)
4: LinReg (ax + b) – this means the calculator will find a line of best fit!
IF YOU HIT ENTER HERE, IT WILL GIVE YOU THE INFORMATION FOR THE
LINE OF BEST FIT, BUT IT WILL NOT GRAPH THE LINE FOR YOU!!! IF YOU
WANT THE CALCULATOR TO ADD ALL OF THE NUMBERS INTO Y1 FOR YOU,
FOLLOW THE STEPS BELOW…
VARS Y-VARS
1: Function
1: Y1
ENTER
GRAPH
Y = .312X - .985 (This is rounded to three decimal places)
b. What can we say about big cats that live in larger range sizes?
c. What percent of time does a big cat spend pacing if the home range size is 100 km2 ? The home range
size is the x – value!
There are a few ways to find the answer to this one.
First way –
2nd GRAPH (TABLE)
Scroll down to 100 to see what the y value is
Second way –
2nd TRACE (CALC)
1: Value
Type in 100
Either way… y = 30.246 = Percent of time pacing = 30%
d. If a big cat spends 40% of time pacing, what home range size does he live in?
Home range is the Y-value!!!
There are a few ways to find the answer to this one.
First way –
2nd GRAPH (TABLE)
Scroll down to find 40 on the y-values. This may not be an exact value
Second way –
Y = Type 40 into Y2
GRAPH
2nd TRACE (CALC)
5: intersect
First curve? (ENTER) Second curve? (ENTER) Guess? (ENTER)
Either way… x = 131 = Home Range size = 131 km2