7th Grade Math

264 Proportions and Similarity

Text Option Take the Quick Check below. Refer to the Quick Review for help.

You have two options for checking

prerequisite skills for this chapter.

Y

p

Are You ReadyAre You Ready

for the Chapter?for the Chapter?

Online Option Take the Online Readiness Quiz.

FIELD TRIPS Write each ratio as a fraction

in simplest form.

1. adults : students Seventh-Grade
   Field Trip
   Students 180
   Adults 24
   Buses 4


2. students : buses


3. buses : people


4. adults : people


5. students : people

EXAMPLE 1

SOCCER Write the ratio Madison Mavericks

Team Statistics

Wins 10

Losses 12

Ties 8

of wins to losses as a

fraction in simplest

form.

wins

(^)
losses
1210 = ^56
The ratio of wins to losses is _^5
6
.
Determine whether the ratios are
equivalent. Explain.

6. 20 nails for every 5 shingles,
   12 nails for every 3 shingles


7. 2 cups of flour to 8 cups of sugar,
   8 cups of flour to 14 cups of sugar


8. 12 out of 20 doctors agree,
   6 out of 10 doctors agree


9. 2 DVDs to 7 CDs,
   10 DVDs to 15 CDs


10. 27 students to 6 microscopes,
    18 students to 5 microscopes

EXAMPLE 2

Determine whether the ratios 250 miles

in 4 hours and 500 miles in 8 hours are

equivalent.

Method 1

Compare the ratios written in simplest form.

250 miles : 4 hours = _^250

4

or _^125

2

500 miles : 8 hours = _^500

8

or _^125

2

The ratios simplify to the same fraction.

Method 2

Look for a common multiplier relating the

two ratios.

× 2

_^2504 = _^5008 The numerator and denominator of the

ratios are related by the same multiplier, 2.

×^2

The ratios are equivalent.

262_264_C05_CO_895130.indd 264 12/29/09 1:03 PM