Percentage Problem

[Guest guest]

Dear All,

I received the following from GD in WA in a private email:

" Jeanetta, Here is the question that I stumble on. If 3.6g of Phenol

is mixed with 16.4g of glycerin, what is the resulting percentage

concentration of Phenol?

10%

18%

20%

36%

Thank you.

GD in WA "

The MAIN theme in solving percentage problems is to identify the

parts of the whole.

So the WHOLE thing is equal to what the two parts add up to!

3.6 gms of Phenol + 16.4 gms of glycerin = 20 gms total P/G combo

NOW let us find out the percentage. PER Cent age means some PART over

the WHOLE times ( multiplied by) 100.

Per means over or divided by 100.

Okay so we now KNOW that in that combo of P/G there is 3.6 grams of

Phenol. BUT the combo is 20 grams of P/G

3.6 gms Phenol = the PART

---------------------------- = OVER

20 gm Phenol/glycerin combo = the WHOLE

OR

3.6 gms P

------------ X 100 = 18%

20 gms P/G

Another way is to use ratio/proportion. recall any number of grams of

a substance over (dividd by or per) 100 equals the same amount of

percent (%):

Set-Up

3.6 gms P........X gms P

------------ = ---------- = 18%

20 gms P/G.....100 gmsP/G

Cross Multiply:

3.6 gms P x 100 gms P/G

----------------------- = X gms

20 gms P/G

18gms P = X gmas P

18 gms P

------------ = 18% Phenol

100 gms P/G

Here is another 'twist' on the same problem. NOW what is the

percentage of glycerin ONLY?

We can do this one of three ways:

1. difference between two components (in percent), recall differenct

implies subtraction.

2. Parts over the whole equation for the glycerin only.

3. Set up a ration/proportion

1. 100% P/G - 18% P = X G% , therefore X% G = 82% glycerin.

2. Parts over the whole method:

16.4 gms G = {the Part)

------------------------ x 100% P/G= 82% G

20 gms P/G (the Whole)

3. Set up

16.4 gms G..........X gms G

------------ = -------------

20 gms P/G........100 gms P/G

Cross Multiply

16.4 x 100

----------- = X gms G = 82 grms G

20

82 gms G

------------ = 82% G

100 gms P/G

I have shown you three different ways to approach this problem.

Ultimately they ALL three began with the knowledge of the TOTAL and

the Parts or the PARTS and the WHOLE, of which you had to calculate

the WHOLE in the VERY BEGINNING. Chosse which way ou like to do this

problem. Then put it in your memory bank.

Try this problem:

Component A is 300 mg

Component B is 1 gram

Component C is 750 mg

What is the percentage of each component if 1.95 gram of Aquaphor is

added as a base for this ointment?

Come back later to find the answer and how to do this problem. I will

post the answer AFTER you give it a try and post your answers. It is

not about who's answer is first, but rather if YOUR answer correct.

Respectfully,

Jeanetta Mastron CPhT BS

Pharm Tech Educator

Founder/Owner