Digits, Grade 8, Volume 1, Homework Helper

2-8: Additional Problem Solving

Part 1

Example Comparing Rates in Different Forms

Which of the three sea animals is the fastest? How do you know?

A Bottlenose Dolphin can travel 8.5 mi every 1 half h.

A graph.

Solution

Find each speed in miles per hour and compare.

Dolphin: fraction 8.5 , mi , over 1 half , h end fraction . equals . fraction 17 , mi , over 1 h end fraction .

The dolphin can travel at a speed of 17 mi/h.

Orca: Use the points (2, 69) and (0, 0) to find the slope of the line. The slope of the line is equivalent to the speed of an orca in miles per hour.

table with 3 rows and 2 columns , row1 column 1 , slope , column 2 equals . fraction 69 minus 0 , over 2 minus 0 end fraction , row2 column 1 , , column 2 equals , 69 over 2 , row3 column 1 , , column 2 equals , 34.5 , end table

The orca has a speed of 34.5 mi/h.

Sea lion: The ratio fraction distanceopenmiclose , over timeopenminclose end fraction shown in each row of the table is equivalent to 2.4 mi/min. The table shows sea lions can travel 25 mi in 60 min. Since 60 min = 1 h, a sea lion can travel at a speed of 25 mi/h.

The orca is the fastest of the three sea animals.


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Table of Contents

Digits, Grade 8, Volume 1, Homework Helper Unit A: Number and Operations Unit B: Proportionality Unit C: Expressions, Equations, and Relationships English/Spanish Glossary Formulas Math Symbols Formulas Measures Properties