Lesson 3C Variation 409- BOOKS One month, the Allen family had a total of $3.20 in fines for
4 books. The next month, they had 7 books overdue for $5.60. What
was the overdue charge per book?
ALGEBRA If y varies directly with x, write an equation for the direct
variation. Then find each value.- If y = -14 when x = 8, find y when x = -12.
- Find y when x = 15 if y = 6 when x = 30.
- If y = -6 when x = -24, what is the value of x when y = -7?
- Find x when y = 14, if y = 7 when x = 8.
- Find y when x = 9, if y = 16.4 when x = 8.2.
1717 MEASUREMENT The number of yards in aYards4681012141618202
0
Feet4 8 12 16 2024 28 3236measure varies directly with the number
of feet. Using the graph at the right,
find the measure of an object in yards
if it is 78 feet long.- BAKING A cake recipe requires 3 ^1
4
cups of
flour for 13 servings and 4 ^1
2
cups of flour for
18 servings. How much flour is required to
make a cake that serves 28? - MULTIPLE REPRESENTATIONS Robert is in charge of the community
swimming pool. Each spring he drains it in order to clean it. He then
must refill the pool, which holds 120,000 gallons of water. Robert fills the
pool at a rate of 10 gallons each minute.
a. WORDS What is the rate at which Robert will fill the pool? Is it constant?
b. GRAPH Create a graph of the relationship.
c. ALGEBRA Write an equation for the direct variation. - MATH IN THE MEDIA Find an example of a graph of a linear function in
a newspaper or magazine, or on the Internet. Determine if the graph
represents a direct variation. Explain your reasoning.
Real-World Link
The typical
American
consumes four
times as many
Calories from
sugar, flour, and
seed oils as from
meat.RRR
T- OPEN ENDED Identify two additional values for x and y in a direct
variation relationship where y = 11 when x = 18. - CHALLENGE Find y when x = 14 if y varies directly as the square of x,
and y = 72 when x = 6. - E WRITE MATH Write a real-world problem involving a direct
variation. Then solve your problem.
404_415_C07_L3_895130.indd 409 12/31/09 4:33 PM