7th Grade Math

Estimate _^14 % of 589.

_^1

4 % is one fourth of 1%. 589 is about 600.

1% of 600 = 0.01 · 600 Write 1% as 0.01.

= 6 To multiply by 1%, move the decimal point two places

to the left.

One fourth of 6 is _^14 · 6 or 1.5. So, _^14 % of 589 is about 1.5.

Estimate.

c. 174% of 200 d. 298% of 45 e. 0.25% of 789

CELL PHONES In a recent year, there were about 200 million

people in the U.S. with cell phones. Of those, about 0.5% used

their phone as an MP3 player. Estimate the number of people

who used their phone as an MP3 player.

0.5% is half of 1%.

1% of 200 million = 0.01 · 200,000,000

= 2,000,000

So, 0.5% of 200,000,000 is about _^12 of 2,000,000 or 1,000,000.

About 1,000,000 people used their phone as an MP3 player.

f. ATTENDANCE Last year, 639 students attended a summer camp.

Of those who attended this year, 0.9% also attended last year.

About how many students attended the camp two years in a row?

Examples 1–4 Estimate.

1. 52% of 10 2. 7% of 20 33 38% of 62


2. 79% of 489 5. 151% of 70 6. _ 21 % of 82


3. BIRTHDAYS Of the 78 teenagers at a youth camp, 63% have birthdays in
   the spring. About how many have birthdays in the spring?

Example 5 8. GEOGRAPHY About 0.8% of the land in Maine is federally owned.

If Maine has 19,847,680 acres, about how many acres are federally owned?

Real-World Link

The American Camp

Association (ACA)

reports that 10 million

children attend camp

annually.

RR

T

Lesson 1C Percents 327

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