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Alan S. TussyR. David Gustafson

PrealgebraSecond Edition

Copyright © 2002 Wadsworth Group.

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8.1 Ratio

In this section, you will learn about

• Ratios • Rates • Unit rates • Unit costs

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Real-life ratios

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Ratios

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EXAMPLE 2 Carry-on luggage.

Airlines allow passengers to carry a piece of luggage onto an airplane only if it will fit in the space shown in Figure 8-1. What is the ratio of the length of the space to its width?

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Rates

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Rates

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Unit rates

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Computing gas mileage

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Unit costs

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EXAMPLE 7 Comparison shopping.

Olives come packaged in a 10-ounce jar, which sells for $2.49, or in a 6-ounce jar, which sells for $1.53. (See Figure 8-3.) Which is the better buy?

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8.2 Proportions

In this section, you will learn about

• Proportions • Means and extremes of a proportion • Solving proportions

• Writing proportions to solve problems

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Ladders - the 4-to-1 rule

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Proportions

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Means and extremes of a proportion

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Means and extremes of a proportion

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Solving proportions

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Solving proportions with a calculator

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Writing proportions to solve problems

EXAMPLE 6 Grocery shopping. If 5 apples cost $1.15, how much will 16 apples cost?

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EXAMPLE 7 Scale drawing.

A scale is a ratio (or rate) that compares the size of a model, drawing, or map to the size of an actual object. On the next page, the airplane in Figure 8-5 is drawn using a scale of 1 inch: 6 feet. This means that 1 inch on the drawing is actually 6 feet on the plane. The distance from wing tip to wing tip (the wingspan) on the drawing is 5 inches. What is the actual wingspan of the plane?

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EXAMPLE 7 Scale drawing.

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8.3 American Units of Measurement

In this section, you will learn about

• American units of length • Converting units of length

• American units of weight • American units of capacity • Units of time

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American units of length

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EXAMPLE 1 Measuring the length of a nail.

To the nearest ¼ inch, find the length of the nail in Figure 8-7.

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EXAMPLE 2 Measuring the length of a paper clip.

To the nearest ⅛ inch, find the length of the paper clip in Figure 8-8.

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EXAMPLE 3 Measuring the length of a ticket.

Find the length of the tear-off part of the concert ticket in Figure 8-9.

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Converting units of length

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Finding the length of a football field in miles

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American units of weight

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Finding the weight of a car in pounds

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American units of capacity

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Units of time

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EXAMPLE 9 Astronomy.A lunar eclipse occurs when the Earth is

between the sun and the moon in such a way that the Earth’s shadow darkens the moon. See Figure 8-10 (which is not to scale). A total lunar eclipse can last as long as 105 minutes. How many hours is this?

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8.4 Metric Units of Measurement

In this section, you will learn about

• Metric units of length • Converting units of length

• Metric units of mass • Metric units of capacity

• Cubic centimeters

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Metric units of length

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Metric ruler

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EXAMPLE 1 Measuring the length of a nail.

To the nearest centimeter, find the length of the nail in Figure 8-13.

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EXAMPLE 2 Measuring the length of a paper clip.

To the nearest ⅛ inch, find the length of the paper clip in Figure 8-8.

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EXAMPLE 2 Measuring the length of a paper clip.

To the nearest millimeter, find the length of the paper clip in Figure 8-8.

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Converting units of length

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Converting units of length

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Metric units of mass

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Metric units of capacity

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Metric units of capacity

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Cubic centimeters

1 mL = 1 cm3 = 1 cc

5 cc = 5 mL

1,000 cc = 1,000 mL = 1 liter

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8.5 Converting between American

and Metric Units

In this section, you will learn about

• Converting between American and metric units

• Comparing American and metric units of temperature

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Converting between Americanand metric units

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EXAMPLE 1 Clothing label.

Figure 8-17 shows a label sewn into some pants made in Mexico for sale in the United States. Express the waist size to the nearest inch.

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Equivalent Weights and Masses

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Equivalent Capacities

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Comparing American and metricunits of temperature

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Conversion formulasfor temperature