Thursday, December 12, 2013

This is Sarah's Percent Post

Hi, this is my percents post.

1) Introduction to percents
-To find 50% of a nber all you have to do is divide the number by 2.
-When you're looking for 10% of a number you divide the number by 10.
-to find 1% of a number you can divide the number by 100.
-Looking for 25% of a number is easy, just divide it by 4!
-Deffinition for percent: Cent in french means 100. So percent means per one hundred. One part in every hundred.


-12 3/4%


To convert 26% into a decimal you must first divide 26% by 100, (26÷100=0.26) giving you the answer of 0.26. 0.26 is the decimal number.

Now to find the fraction you take the decimal, 0.26, and read it out loud. Twenty six hundredths. Being twenty six hundredths you make the denominator 100, because the decimal place value is in the hundredth. Now that you got the denominato, 100, you must now find the numirator which is 26 ( from 0.26). So you get the fraction 26/100

First you must convert 7/10 into a decimal. You do this by dividing the numirator by the denominator. 7÷10=0.7. Now you have the decimal!!!

To find the percent from here you take the decimal number, 0.7, and multiply it by 100. 0.7x100=70%.

To convert this decimal number into a percent yoy have to take the decimal number and multiply it by 100. 0.024 x 100= 2.4%.
Now you have the percent!

Now for making the fraction you have to find the place value of the decimal. it is zero and twenty four thousandths. So disregard the zeros in 0.024 and put 24 as the numirator and 1000 as the denominator. 24/1000

-20% of 60.
To find 20% of 60 useing mental math you coul follow this trick I like to use.
1- 20% of 60
12 is the answer!
20%divided by 100=0.2
Useing a calculator you could divide 60 by 10. then when you get the answer (6) you double it (6+6=12).

-0.1% of 40
To find 0.1% of 40 you can do:
-0.1%divided by 100=0.001

-250% of 400.

To find 250% of 400 you could do the following steps:
    1-  100% of 400 = 400
  2- knowing 100% of 400 all you have to do is double the answer (400) to get 200% 400+400=800.
     3- 50% is half of 100%. So you can just find half of 100%, which is 200. (400 divided by 2=200)
    4- Now it's time to add it all up. 200%=800

you might just know that 250% of 400 will be larger than 400 because 250% is an improper fraction (250/100) know that the whole number is 400. 250/100=2 50/100 or 2 1/2 so what are 2 wholes? 400+400=800 and what is half of our whole? 200. So 200+800=1000!
-Question #7 on page 149:
A herd of 100 caribou was moved to a new location. The population increased by 10% the first year, then increased by 20% the second year.

a) Find the population after the second year.
-First yerar increased by 10%. 
10% of 100 is 10 because:
-100 divided by 10 =10
In the first year it increased by 10 caribous the answer is 110 because -10+100=110
-Second year increased by 20%.
20% of 110 is 22 because:
110 divided by 10=11
By the second year it has increased by 22 caribous. making the total number of caribous 132 after the second year.

b) Explain why there was not a 30% increase in population over the two years.
The reason why there is not a 30% increase after the two years is because you had to find 20% of a number that had already been increased by 10%. The answer to the question above was 132 but if you were to find 30% of 100 it would be 30 making the final number 130. It does matter weather you follow the given instructions to find and add a percent and the add to that percent rather than just combining all the percents together. There is no 30% increase because it was not the question
 to find 30% of 100.
-So going back to the question what is a better deal 50% off or 25% off of an already reduced price of 25% the better deal would be 50% off because:
say the origiinal price was $100. 50% off would be $50, ($100 divided by 2=$50)but 25% off $100 would be $75 ($100 divided by 4= $25, $100-$25=$75) then 25% off of $75 would be $56.25 ($75 divided by 4=$18.75, $75-$18.75=$56.25.).

 *Hope you all like this video. It helped me understand how to find percent and what a percent is in a more clearer and visual way.* :)


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