Page 631 - Basic College Mathematics with Early Integers

608 C HAPTE R 8 I INTRODUCTION TO ALGEBRA

Definitions and Concepts Examples

Section 8.5 Equations and Problem Solving

PROBLEM-SOLVING STEPS The incubation period for a golden eagle is three times
the incubation period for a hummingbird. If the total of
1. UNDERSTAND the problem. Some ways of doing
their incubation periods is 60 days, find the incubation
this are
period for each bird. (Source:Wildlife Fact File,
Read and reread the problem.
International Masters Publishers)
Construct a drawing.
Choose a variable to represent an unknown in the 1. UNDERSTAND the problem.Then choose a variable
problem. to represent an unknown. Let
x = incubation period of a hummingbird
3x = incubation period of a golden eagle
2. TRANSLATE the problem into an equation. 2. TRANSLATE.
incubation incubation
of + of is 60
hummingbird golden eagle

T T T T
x + 3x = 60
3. SOLVE the equation. 3. SOLVE:
x + 3x = 60
4x = 60
1
4x 60
=
4 4
1
x = 15
4. INTERPRET the results. Check the proposed solution 4. INTERPRET the solution in the stated problem.The
in the stated problem and state your conclusion. incubation period for a hummingbird is 15 days.The
incubation period for a golden eagle is
#
3x = 3 15 = 45 days.
Since 15 days + 45 days = 60 days and 45 is 3(15),
the solution checks.
State your conclusion:The incubation period for a
hummingbird is 15 days.The incubation period for a
golden eagle is 45 days.

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