finding a number when a percentage of it is known

aimeemae02

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Mar 18, 2007
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2/3% of (?)=33.3

do you change the percent into a decimal which equals .66 repeating?? I'm stuck from there
 
Use Algebra.

[(2/3)/100]X = 33.3

We divide by 100 so the decimal equivalent of (2/3)% is correct

simplify: ---> (1/150)X = 33.3

solve for X by multiplying both sides by 150, to get X by itself.
 
I am very confused can you put it in easier terms... sorry this doesn't come easy at all to me
 
aimeemae02 said:
I am very confused can you put it in easier terms... sorry this doesn't come easy at all to me

Not a problem! Normally we dont do lessons...But Here we GO...

You want to find (2/3)% of (?) which equals 33.3

We want to begin by putting (2/3)% in it's decimal form: so we divide by 100. ---> (2/3) / 100 is the same as doing (2/3) * (1/100) (we multiplied by the reciprocal so we don't have to fuss about the division symbol. We get (2/300) which can be reduced down to (1/150)

SO

(1/150) is the decimal equivalent of (2/3)%, after we divided by 100

now we can start some simple algebra.
(1/150) of (?) is equal to 33.3

so we can replace the (?) with an X. (an unknown)
We know that the use of the word "of" means, multiply by...so we can go ahead and put the (1/150) right next to the X

(1/150)X = 33.3
Now... we want to get X by itself.. so we want to do the opposite of division to get rid of the (1/150)X

We multiply both sides by 150
150(1/150)X = 33.3(150)

now we have 1X = 33.3(150)
so, X = 33.3(150)

we can now conclude from our math that (2/3)% of (33.3(150)) = 33.3

So, (2/3)% of 4995 = 33.3
Makes sense right?
 
aimeemae02 said:
2/3% of (?)=33.3
do you change the percent into a decimal which equals .66 repeating?? I'm stuck from there

simply divide: 33.3 / (2/3) = 49.95
then multiply by 100: 4995 (because it is a percentage)

Note: it is easy to divide by a fraction; invert fraction, then multiply:
3/2 * 33.3 = 99.9/2 = 49.95
 
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