Transcript GEPA Lesson 6 - Henry Hudson Regional School

GEPA Lesson 6
Fractions, Decimals, and Percents
Percent means hundredths
• 75% means:
75/100
or 0.75
• 4% means:
4/100
or 0.04
• 150% means:
150/100
or 1.50
(think in terms of money: 75 cents, 4 cents, one dollar and 50 cents)
You can also think of changing a percent to a
decimal by dropping the % symbol and
moving the decimal point 2 places to the left
30% = 0.30
3% = 0.03
125% = 1.25
Example # 1
Jed changed 8% to a decimal in order to determine the
amount of tax he would have to pay on his purchase of a
guitar. Which correctly represents 8%?
A. 0.08
B. 0.8
C. 8.0
D. 800
8% means 0.08
(think in terms of money: 8 cents out of 100 cents, or .08)
or
8% = 0.08
(move decimal point 2 places to the left)
Thus, 8% is represented by 0.08, choice A.
Example # 2
35% of the students in the eighth grade at Ramsey Junior
High are in sports. What fraction of the students is that?
A. 35/10
B. 3/5
C. 7/20
D. 35/1000
35% means 35/100
Now reduce this fraction to lowest terms.
35/100 = 7/20 (divide the numerators and
denominator by 5)
Thus, the fraction of students is 7/20, choice c.
TRY THESE:
# 1.) Write 6% as a decimal.
#2.)
Write 145% as a decimal.
#3.)
Write 40% as a fraction reduced to lowest terms.
#4.) What are two ways you can change a percent into a
decimal?
#5.) How can you change a percent into a fraction?
You can change a fraction to a percent
by dividing the numerator by the
denominator. If the division is not
exact, carry our the division to the
thousandths place. Then, you might
round the results to the nearest
hundredth and write the results as a
percent. However, the GEPA might
indicate an APPROXIMATION in the
multiple choice that is NOT this
rounded answer.
(this is illustrated in the following example.)
Example # 3
Six-sevenths of Ms. Jamison’s girl scout troop
planned to attend a baseball game. APPROXIMATELY
what percent of the troop was that?
A. 11%
B. 67%
C. 76%
D. 85%
Divide 7 into 6.000
7 into 6.000 = 0.857
But, the APPROXIMATE answer from dividing
mentally to two decimal places is 0.85.
As a percent, 0.85 is 85%
Thus, the APPROXIMATE % is 85%, choice D
TRY THESE:
# 6.) Two-sevenths of Mr. Johnson’s math class failed
the last math test. APPROXIMATELY what percent
of the class was that?
A. 2%
B. 28%
C. 35%
D. 280%
Example # 4
Find a number between 7/25 and
30%
Write 7/25 and 30% each as a decimal.
7/25 = 7 ÷ 25 = 0.28
30% = 0.30
So, a number between 0.28 and 0.30 could
be:
0.29
Example # 5
Which number below does NOT represent the shaded
portion of the figure?
A. 5/8
B. 62.5
C. 62 ½
D. 0.625
5 out of 8 blocks are shaded.
5/8 of the region is shaded.
First change 5/8 to a decimal, in hundredths.
Divide 8 into 5.00
5/8 = 0.625 OR 0.62 ½
Write 0.62 ½ as a percent : 62 ½ %
So, 5/8 , 0.625 , or 62 ½% all represent the shaded portion of the
figure.
The shaded portion is NOT represented by the only remaining choice,
62.5, choice B.
TRY THESE:
# 7.) Which number below does NOT represent the
shade portion of the figure ?
A. 0.0375
B. 37.5%
C. 37 ½%
D. 3/8
# 8.) How do you find a percent between a fraction and
a percent?
# 9.) Find a percent between 1/20 and 3%.
Example # 6
Which of the numbers below is equivalent to 0.3?
A. 3%
B. 0.9
C. 30%
D. 0.31 - 1
Write each multiple choice as a decimal to compare with 0.3 .
1) First consider choice A. 3% = 0.03 (this is not 0.3)
2) Now consider choice B.
0.9 = 0.948683298 (this is not 0.3)
3) Now consider choice C.
30% = 0.30 (this IS 0.3 or 0.30)
So, 0.3 is equivalent to 30%, choice C.
TRY THIS:
# 10.) Which numbers below is NOT equivalent
to 0.02 ?
A. 2%
B. 0.0004 C. 200% D. 1/50
Now complete the second worksheet
(example7). Read each direction carefully.
Show your work.