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#1 2006-07-17 18:52:37

booboo12
Member
Registered: 2006-07-11
Posts: 5

couple ?'s

Can you show me how or lead me to the page to solve the following problems?

Convert 6 5/8% to a decimal.


75% of what number is 36.



45 is what percent of 75

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#2 2006-07-17 21:34:35

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,551

Re: couple ?'s

Ignore the "%" for the moment: 6 5/8 = 6+5/8 = 6+0.625 = 6.625
Now think of it as % (read about Decimals, Fractions and Percentages): 6.625% = 0.06625

For the next problem, have a go at the slider on Percentages, put 100%=36 and then see what 75% is.


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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#3 2006-07-18 19:37:17

John E. Franklin
Member
Registered: 2005-08-29
Posts: 3,562

Re: couple ?'s

I'll attempt "45 is what percent of 75".
First an estimate is always a good idea so you sort of check your work to make sure it is close to right.
So first of all look at 45 and say it's between 10 and 100, and then so is 75 between 10 and 100.
So because 10 is 10 times less than 100 and 100 is ten times more than 10, we can say the
following:
10 is 10% of 100 and also 100 is 1000% of 10.
So because 45 and 75 are between 10 and 100, we know our answer is between 10% and 1000%.
So that's a start.
Next 45 is smaller than 75, and smaller by 30 because 45 + 30 = 75.
So let's make some more guesses...
       45               +                  30           =           75

     50%               +                 50%        =          100%

  I guessed 50% above for 45 and for 30 and 50% means a half.
50% plus 50 percent is 100% which means the whole thing because 100% means whole thing or 1 thing.


igloo myrtilles fourmis

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#4 2006-07-18 19:53:11

John E. Franklin
Member
Registered: 2005-08-29
Posts: 3,562

Re: couple ?'s

Now 50% for 45 and 50 % for 30 isn't exactly right, but it's a good start depending how accurate you want to get.
It's not perfect because 45 and 30 are different numbers, but 50 and 50 are the same!!
We want to make one 50 go up a little and the other 50 go down a little so they are more like 45 and 30 going up and down.
But the difference is that 45 and 30 add up to 75, and our two #'s percent have to add to 100 because
the percentages add to 100% to make the whole thing.

I just figured out the answer!!! It's  60% and 40%, but how did I do it??  Well, I decided to reduce 45 and 30 down smaller like you do to fractions to see what happens.

45   +   30  =   75
Divide by 15 since everything divides by 15.
45/15  +  30/15  = 75/15

3    +       2       =    5

Does this help??
Instead of 45 is what percentage of 75, now we have 3 is what percentage of 5.

Let's add zeros for fun...

30 + 20 = 50

Let's add more zeros for zeal, whatever that means...

300 + 200 = 500

We want it to add to 100% though.

300% + 200% = 500%

Cut them in half.

150%  + 100%  = 250%

We want 100%, not 250% for the whole thing.

25 is like a quarter, so multiply by 4 to make a dollar.

(150 x 4)  %  +  (100 x 4)%  =  (250 x 4)  %

600% + 400% = 1000%

Hmmmm, not 1000%, we want 100%.

Take off a zero off each one.

60% + 40% = 100%

Yeah!!!!!!!!!!  We did it.  45 is 60% of 75.    and 30 is 40% of 75.


igloo myrtilles fourmis

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#5 2006-07-18 19:58:29

John E. Franklin
Member
Registered: 2005-08-29
Posts: 3,562

Re: couple ?'s

I found another way to do 45 is what % of 75.
45 + 30 = 75
15 + 10 = 25  because I divided everything by 3.
Add the last two equations together.
  45    30     75
+15  +10   +25
-----  -----   -----
60     40     100

Yeah  60% + 40% = 100%
We did it!!!!!!!!!!!!!


igloo myrtilles fourmis

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#6 2006-08-13 15:11:34

fusilli_jerry89
Member
Registered: 2006-06-23
Posts: 86

Re: couple ?'s

John E. Franklin wrote:

I found another way to do 45 is what % of 75.
45 + 30 = 75
15 + 10 = 25  because I divided everything by 3.
Add the last two equations together.
  45    30     75
+15  +10   +25
-----  -----   -----
60     40     100

Yeah  60% + 40% = 100%
We did it!!!!!!!!!!!!!

uhh, or you could just divide 45 by 75 which gives you 0.6.....

and for the second question, just write a simple equation, 0.75x=36, which means 75% of a number(x) equals 36. Solve and you get 48.

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