Download Chap 5 - 05 - Safford Unified School

Lesson 5-1 Ratios and Percents
Write each ratio or fraction as a percent.
1. According to the 2000 U.S. Census, 13
out of every 100 people living in
Delaware were 65 or older.
Percent – a ratio that compares a
number to 100.
Per “cent” = per 100
20% means 20 out of 100 =
2. In 2001, Manny Ramirez got on base
40.5 times for every 100 times he was
at bat.
20  20
= 1
100  20
5
To change a ratio to percent:
1. Write the ratio as a fraction.
2. Make this fraction equal to
100
3. About 4 out of 5 commuters in the
U.S. drive or carpool to work.
3
4. In 2000, about 200 of the population
in Peru used the Internet.
3. Figure out what number you would
have to multiply the denominator
by to get 100.
4. Multiply and write as a percent.
Write the ratio 4 out of 25 as a percent.
4  4
= 16 = 16%
100
25  4
Or:
5. The circle graph shows an estimate of 1. Write as a fraction.
2. Make this fraction equal to
the percent of his day that Peter
spends on each activity. Write the
percents for eating and sleeping as
fractions in simplest form.
.
100
.
3. Do backwards Z; divide the 1st
denominator into the 2nd.
4. Multiply that answer by the
numerator.
5. Write as a percent.
4
= 16 = 16%
100
25
25 into 100 goes 4 times. 4 times 4 = 16.
Glencoe Math App & Con (2006) – Course 3
Lesson 5-2 Fractions, Decimals, and Percents
Decimal to Percent:
Write each percent as a decimal.
1. Multiply by 100.
1. 52%
2. Add the percent symbol.
0.53 x 100 = 53%
2. 245%
Percent to Decimal:
1. Divide by 100.
2. Remove the % symbol.
Write each decimal as a percent.
64% = 64 100 = 0.64
3. 0.3
Express a fraction as a percent.
1. Write as a proportion.
2. Find the cross product.
3. Solve the equation.
4. 0.71
3
=
100
4
Write each fraction as a percent.
5.
3
4
3 • 100 = 4x
300 = 4x
4
4
75 = x
6.
75
= 75%
100
1
6
7. In Sun City,
9
of voters are
20
Democrats. In Moon Town, 48%
of voters are Democrats. In
which town is there a greater
proportion of Democrats?
Glencoe Math App & Con (2006) – Course 3
Lesson 5-3 Algebra: The Percent Proportion
Percent Proportion:
1. 34 is what percent of 136?
wp
is
=
100
of
2. What number is 70% of 600?
wp = what percent
“ What percent over 100 equals “is”
over “of”?”
What is 40% of 160?
40
x
=
100
160
40(160) = 100x
3. From 1999 to 2001 Derek Jeter
had 11 hits with the bases loaded.
This was about 30% of his at
bats with the bases loaded. How
many times was he at bat with
(Think – alphabetical order for is and of.)
the bases loaded?
**** Set up in proportion, then solve
using cross-products and solving the
equation.
4. In a certain small town, 63% of
the adults are college graduates.
How many of the 240 adults
living in the town are college
graduates?
Remember – when it asks “what
percent”, your answer has to have a
percent sign.
Glencoe Math App & Con (2006) – Course 3
Lesson 5-4 Finding Percents Mentally
1. 40% of 80.
2
3
2. 66 % of 75.
Copy the chart on page 220.
Change the common percent to a
fraction.
Then divide by the denominator and
multiply by the numerator.
1
x 45
5
(Think: 45 divided by 5, times 1)
20% of 45 =
3. 10% of 65.
4. 1% of 304.
5. A company produces 2,500 of a
particular printer. They later
discover that 25% of the printers
have defects. How many printers
from this group have defects.
Glencoe Math App & Con (2006) – Course 3
Lesson 5-5 Percent and Estimation
Estimate.
Compatible numbers – two numbers
that are easy to divide mentally.
1. 48% of 70.
Find 19% of 60.
2. 75% of 98.
20% would be easier to find as it is
compatible to 60.
20% = 1 and 1 of 60 =
5
3. 12% of 81.
Estimate each percent.
4. 12 out of 47.
5
1
x 60 = 60 = 12
1
5
5
Sometimes you have to change both
numbers. Find the closest to each.
34% of 88
34 is closest to 33⅓% which is 1 .
3
5. 19 out of 31.
88 is closest to 87
which is divisible by 3.
6. 41 out of 200.
1
x 87 = 87 = 29
3
1
3
7. An artist creates a design on a
grid. Estimate the percent of the
grid that has been painted so far.
Glencoe Math App & Con (2006) – Course 3
Lesson 5-6 Algebra: The Percent Equation
1. Find 30% of 450.
Change the words to an equation:
What number is 25% of 60?
n=
1
x 60
4
2. 102 is what percent of 150?
15 is what percent of 60
15 = n (60)
3. 144 is 45% of what number?
15 is 25% of what number
15 =
1
n
4
4. The price of a sweater is $75.
3
4
The sales tax is 5 %. What is
the total price of the sweater?
Glencoe Math App & Con (2006) – Course 3
Lesson 5-7 Percent of Change
1. The Nietos bought a house
several years ago for $120,000.
This year, they sold it for
$150,000. Find the percent of
increase.
Percent of Change – when an increase
or decrease is expressed as a percent.
Find the percent of change:
a. Find the amount of change.
b. Put the change in the numerator.
c. Put original (beginning, first)
number in the denominator.
d. Solve proportion.
Original: 85
2. Johnson Middle School had 240
students last year. This year,
there are 192 students. Find the
percent of change. State
whether this percent of change is
an increase or a decrease.
New: 112
112 – 85 = 27
change
wp
=
100
original
wp
27
=
100
85
100(27) = 85wp
3. Shirts bought by a sporting
goods store cost them $20 per
shirt. They want to mark them
up 40%. What will be the
selling price?
The percent of discount:
A phone that sells for $130 is
marked down 30%.
Sale
70%
x
Original
100
$130
a. 100% subtract percent off.
b. Solve proportion.
4. A computer usually sells for
$1,200. This week it is on sale
for 30% off. What is the sale
price?
Sale
Original
Glencoe Math App & Con (2006) – Course 3
Lesson 5-8 Simple Interest
1. Find the simple interest for
$2,000 invested at 5.5% for 4
years.
Interest – the amount paid or earned
for the use of money.
Principal – the amount of money
invested or borrowed.
l = prt : Interest equals principal times
rate times time.
2. Find the total dollar amount in
an account thwere $80 is
invested at 6% for 6 months.
Total Amount:
a. Find the interest.
b. Add the principal and interest.
Find the interest:
$500 at 7% interest for 4 years.
I = $500(0.07)(4) = $140
3. Gerardo borrowed $4,500 from Total Amount: $500 + $140 = $650
his bank for home
improvements. He will repay
the loan by paying $120 a month
for the next four years. Find the
simple interest rate of the loan.
Glencoe Math App & Con (2006) – Course 3