242 CHAPTER 4 Systems of Linear Equations
10.In 2009, the FCI prices for Major League Baseball and the National Football League to-
taled $609.53. The football FCI was $215.75 more than that of baseball. What were the
FCIs for these sports?
Solve each problem. See Example 2.
11.Andrew McGinnis works at Arby’s. During one par-
ticular day he sold 15 Junior Roast Beef sandwiches
and 10 Big Montana sandwiches, totaling $75.25.
Another day he sold 30 Junior Roast Beef sand-
wiches and 5 Big Montana sandwiches, totaling
$84.65. How much did each type of sandwich cost?
(Source:Arby’s menu.)
12.New York City and Washington, D.C., were the two most expensive cities for business
travel in 2009. On the basis of the average total costs per day for each city (which include
a hotel room, car rental, and three meals), 2 days in New York and 3 days in Washington
cost $2772, while 4 days in New York and 2 days in Washington cost $3488. What was the
average cost per day in each city? (Source: Business Travel News.)
Concept Check The formulas (percentage base rate) and (simple
interest principal rate time) are used in the applications in Exercises 17–24.To p re -
pare to use these formulas, answer the questions in Exercises 13 and 14.
13.If a container of liquid contains 60 oz of solution, what is the number of ounces of pure
acid if the given solution contains the following acid concentrations?
(a)10% (b) 25% (c)40% (d) 50%
14.If $5000 is invested in an account paying simple annual interest, how much interest will
be earned during the first year at the following rates?
(a)2% (b) 3% (c)4% (d) 3.5%
15.Concept Check If 1 pound of turkey costs $2.29, give an expression for the cost of xpounds.
16.Concept Check If 1 ticket to the movie Avatarcosts $9 and ytickets are sold, give an
expression for the amount collected from the sale.
Solve each problem. See Example 3.
=
p=br = * I=prt
Gallons Percent Gallons of
of Solution (as a decimal) Pure Alcohol
x
y
20 32 %=
35 %=0.35
25 %=0.25
Liters Percent Liters of
of Solution (as a decimal) Pure Acid
x
y
120 21 %=
33 %=
15 %=0.15
17.How many gallons each of 25% alcohol
and 35% alcohol should be mixed to get
20 gal of 32% alcohol?
18.How many liters each of 15% acid and
33% acid should be mixed to get 120 L
of 21% acid?
19.Pure acid is to be added to a 10% acid solution to obtain 54 L of a 20% acid solution.
What amounts of each should be used?
20.A truck radiator holds 36 L of fluid. How much pure antifreeze must be added to a mix-
ture that is 4% antifreeze to fill the radiator with a mixture that is 20% antifreeze?
