2. REVIEW
Calculate slope of a line that contains these two points
1. (4, 10) (7, 12) 2. (2, 5) (1, 3) 3. (0, 6) (-1, 8)
4. A climber is on a hike. After 2 hours he is at an altitude of 400 feet.
After 6 hours, he is at an altitude of 700 feet. What is the average rate
of change?
Slope in context:
(x,y) X is input or independent variable (Time is independent because it
happens regardless)
y is output or dependent variable ( altitude is dependent on how
many hours the climber is climbing)
5. Lets practice identifying independent versus dependent variables
Khan Academy:
Independent versus dependent variables
6. A climber is on a hike. After 2 hours he is at
an altitude of 400 feet. After 6 hours, he is at
an altitude of 700 feet. What is the average
rate of change?
Which is the independent and dependent
variables? Which is an input and which is an
output?
Determine the two points from the given
information. In this case time in hours is x
while output y is feet.
(2,400) (6, 700)
Now use the points to calculate
slope using slope formula
x1 y1 x2 y2
2 400 6 700
700 400
6 2
300/4 = 75 feet per hour
7. A scuba diver is 30 feet below the surface of the water 10 seconds
after he entered the water and 100 feet below the surface after 40
seconds. What is the scuba divers rate of change?
What are the coordinate points from the information
in the problem?
(____,____) (_____,____)
Calculate slope
What is the independent variable (X)?
What is the dependent variable (y)?
8. A scuba diver is 30 feet below the surface of the water 10 seconds
after he entered the water and 100 feet below the surface after 40
seconds. What is the scuba divers rate of change?
What are the coordinate points from the information
in the problem?
(10,30) (40,100)
Calculate slope
What is the independent variable (X)?
Seconds
What is the dependent variable (y)? Feet
100 30
40 10
70
30
2 1/3 feet/sec
9. A woman weighed 140 lbs. in 1996 and weighs 190 lbs. in 2016.
What was the rate of change in weight?
Which rate sounds correct?
Weight per year or year per weight??
How would we write this as coordinates?
(____,____) (____,____)
10. A teacher weighed 140 lbs. in 1996 and weighs 190 lbs. in 2016.
What was the rate of change in weight?
( 1996, 140) (2016, 190)
=
= 2.5 lbs. per year
13. Try These
1. Katteren started a savings account with $300. After 5 weeks, she had
$350, and after 9 weeks, she had $400. What was the rate of change of
money in her savings account per week?
2. A plane left Chicago at 8:00 A.M. At 1:00 P.M. the plane landed in Los
Angeles, which is 1500 miles away. What was the average speed of the
plane for the trip?
3. After 30 baseball games, a player had 25 hits. If after 100 games he had
80 hits, what is his average hits per baseball game?
14. 1. Katteren started a savings account with $300. After 5 weeks, she had
$350, and after 9 weeks, she had $400. What was the rate of change of
money in her savings account per week? $10 per week
2. A plane left Chicago at 8:00 A.M. At 1:00 P.M. the plane landed in Los
Angeles, which is 1500 miles away. What was the average speed per
hour of the plane for the trip?
300 miles per hour
3. After 30 baseball games, a player had 25 hits. If after 100 games he
had 80 hits, what is his average hits per baseball game? 11/14 or about 0.79
hits per game
15. EXTRA Practice
IXL Find a slope from a graph Code YH9
IXL Find the slope from two points Code VZG
IXL Identify independent and dependent variables 9UJ
Khan Academy: Independent versus dependent variables
Khan Academy:Slope and intercept meaning in context
16. More word problem practice
1. A rental car company charges a base fee and an additional charge based on how many
miles the car has been driven. If one client was charged $59.00 and drove 80 miles and
another client was charged $83.00 and drove 160 miles, what is the cost per mile?
2. Bike rentals are available on the canal. One patron paid $26.00 for 5 hours while another
patron paid $42.00 for 9 hours. What is the average rate of change? How much was the
cost per hour?
3. An airplane is descending for a landing. After 3 minutes, it is at 24,000 feet above the
ground. After 5 minutes, it is 20,000 feet above the ground. What is the rate of change?
17. 4. A hairstylist has to pay each month for her booth. At 12 haircuts she breaks even, and
at 27 haircuts she makes a profit of $285. How much does she charge per haircut?
5. A yoga studio charges a yearly sign up fee, and a per class charge. If Celeste spent a
total of $55.00 after 6 classes and $75.00 after 10 classes. How much does the
studio charge per class?
6. A reception hall charges a reservation fee and a per plate cost for each guest. It
charges $147 for 6 guests and $255 for 15 guests. How much is the cost per guest?
18. Answers
1. (80, $59) (160,$83)
8359
16080
= $0.30 per mile
2. (5,$26) ( 9,$42)
4226
95
= $4 per hour
3. (3, 24,000) (5, 20,000)
20,00024,000
53
= -2000 feet per minute
4. (12,$0) (27, $285)
2850
2712
= $19 per haircut
5. (5, $55) (10,$75)
7555
105
= $4 per class
6. (6, $147) (15, $255)
255147
156
= $12 per plate