Intermediate Algebra (11th edition)

(Marvins-Underground-K-12) #1

Solve each problem. See Examples 8 and 9.


SECTION 2.5 Linear Inequalities in One Variable 101


65.Faith Varnado earned scores of 90 and
82 on her first two tests in English liter-
ature. What score must she make on her
third test to keep an average of 84 or
greater?


66.Greg Tobin scored 92 and 96 on his first
two tests in “Methods in Teaching Math-
ematics.” What score must he make on
his third test to keep an average of 90 or
greater?

67.Amber is signing up for cell phone serv-
ice. She is trying to decide between Plan
A, which costs $54.99 a month with a
free phone included, and Plan B, which
costs $49.99 a month, but would require
her to buy a phone for $129. Under ei-
ther plan, Amber does not expect to go
over the included number of monthly
minutes. After how many months would
Plan B be a better deal?


68.Newlyweds Bryce and Lauren Tomlin
need to rent a truck to move their be-
longings to their new apartment. They
can rent a truck of the size they need
from U-Haul for $29.95 a day plus
28 cents per mile or from Budget
Truck Rentals for $34.95 a day plus
25 cents per mile. After how many miles
would the Budget rental be a better deal
than the U-Haul one?

A product will produce a profit only when the revenue R from selling the product exceeds the
cost C of producing it. In Exercises 69 and 70, find the least whole number of units x that must
be sold for the business to show a profit for the item described.


69.Peripheral Visions, Inc., finds that the cost of producing x studio-quality DVDs is
, while the revenue produced from them is (Cand Rin dollars).


70.Speedy Delivery finds that the cost of making xdeliveries is , while the
revenue produced from them is (Cand Rin dollars).


71.A body mass index (BMI) between 19 and 25 is considered healthy. Use the formula


to find the weight range w, to the nearest pound, that gives a healthy BMI for each height.
(Source: Washington Post.)
(a)72 in. (b)63 in. (c)Your height in inches

72.To achieve the maximum benefit from exercising, the heart rate, in beats per minute, should
be in the target heart rate (THR) zone. For a person aged A, the formula is as follows.


Find the THR to the nearest whole number for each age. (Source:Hockey, Robert V., Physical
Fitness: The Pathway to Healthful Living,Times Mirror/Mosby College Publishing.)
(a) 35 (b) 55 (c)Your age

0.7 1220 - A 2 ...THR...0.85 1220 - A 2


BMI=


704 * 1 weight in pounds 2
1 height in inches 22

R=5.50x

C= 3 x+ 2300

C= 20 x+ 100 R= 24 x
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