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Wednesday, December 18, 2013

Lizley's Percent Post

Percent means
-percent means "out of a hundred"

*This is how to find the percent of a fraction:
 9   X 10  =  90
10  X 10  = 100
= 90%

But why 100?
-100 is used because its easy to use/its a friendly number.

*Meanings

100% - means all, everything, 100 , 100%
                                              100
                                    
50% - means half,  50  , 1 , 50%
                            100   2

25% - means half 50, 25 %, 25 , 100
                                            100    4

10% - means 10010 , 10%
                      10    100

1% - means 1 out of a 100,  1   , 100 , 1%
                                          100     1

But how about 205% ?
-it is improper/top heavy
-it means 2 holes
- 205
  100

Representing Percent


 180%

100

80

0.6%

                                               
12 3
     8


                                 


How to convert from Decimals to Percents to Fraction

1) 26%
-To convert it to become a decimal, you need to divide 26 to 100.
26 ÷ 100 = 0.26

to be simpler, just move the decimal point two spaces to the left.
26. → 0.26

-To convert it to fraction, you just make it 26/100 and simplify it to 13/50

2) 7/10
-To convert it to percent, you just need to divide the numerator to the denominator. Then move the decimal point two spaces to the right.
7 ÷ 10 = 0.7
0.7 → 7. = 7%

-To convert it to decimal is just dividing the numerator to the denominator.
7 ÷ 10 = 0.7

3) 0.024
-To convert decimal to percent, you just need to move the decimal point 2 spaces to the right.
0.024 → 2.4%

-To convert decimal to fraction, you need to convert it to decimal, and count the decimal places. The number before the decimal point will be the whole number.
2.4 → 2 4/10 = 2 2/5

How to get the percent of a number
      
 20% of 60 :

Mental
       %  | #                                                                                                      
÷5 100 | 60  ÷5                                  
       20 |12

Calculator
20 ÷ 100 = 0.20 = 0.2
0.2 x 60 = 12

20% of 60 is 12

                           
0.1% of 40:

Mental
               % | # 
÷10      100 | 40    ÷ 10
÷100      10 | 4      ÷ 100
             0.1 | 0.04

Calculator
 0.1÷100=0.001
0.001 x 40 = 0.04

0.1% of 40 is 0.04

250% of 100
Mental
                 %| #
             100 | 100
÷ 100       1  | 1         ÷100
x 250     250|250       x250

Calculator

100 ÷ 100 = 1
1 x 250 = 250

 

Combining Percents

Discount  - What you save
Sale Price - What you pay
 _____________________

Problem:
 A herd of 100 caribou was moved to a new location. the population increased by 10% the first year and then increased by 20% the second year.
 
a) find the population after the second year.
1. You have to find the 10% of 100 to know the population that increased the 1st year.
 
 
2. Then, add it to 100.
 
100 + 10 = 110
 
3. Find out the 20% of 110, and add it to 110, because 110 is our new total.
 
110 ÷ 100 = 1.1
1.1 x 20 = 22
110 + 22 = 132
 
 

b) Explain why there was not a 30% increase in population over the two years.
If the percent had changed, the final answer would change too.





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