math of course

[Guest guest]

Dear Pam,

Let us begin with:

How much total 2.5 % HC cream do we have?

8 x 1 oz = 8 oz of 2.5% HC cream

We MUST recall (See my math Tutorials) that in a semi-solid (cream/ointment)

or liquid that “X” percent means “X”grams over 100ml (recall 1 cc = 1ml)

Set up a ratio proportion:

2.5 gm………………..X gm

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

100 ml………………..8 oz

Because we have ‘apples’, ‘oranges’ and ‘pineapples ‘ we can not cross multiply

yet. Not until we make the top (numerators) have the same units, and the bottom

(denominators have the same units).

So let us change (convert) the 8 oz to ml.

1 ounce (dry or liquid)…………8oz

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

30 ml…………………………..Xml

Cross multiply:

30 x 8

------- = Xml = 240 ml

1

What we now know we can use to substitute into the ‘original’ ratio proportion

set up

2.5 gm…...X gm

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

100 ml…. 240 ml

Now we have “apples – apples over oranges - oranges”!!!!

That is reason to go on!

Cross multiply

2.5 gm……X gm

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

100 ml…..240 ml

2.5 x 240

----------- = X gm = 6 gram

100 ml

I do hope this helps you out!

I do need the source of your question please! ( the book it came from)

Thank you

Jeaentta Mastron CPhT BSChemistry

Pharm Tech Educator

Founder/owner of this site

p_silby <p_silby@...> wrote:hi jeaneatta i have a question that is

stumping me

What is the total amount of hydrocortisone found in

eight 1 ounce tubes of hydrocortisone cream 2.5%. The

answer is 6gm. I can't figure out how they came up with that.

I've got to be making it harder than it is.

thanks

Pam

[Guest guest]

Dear Pam and ALL,

Let me clean up this presentation, the ratio/proportions are not

lined up...

Dear Pam,

Let us begin with: How much total 2.5 % HC cream do we have?

8 x 1 oz = 8 oz of 2.5% HC cream

We MUST recall (See my math Tutorials) that in a semi-solid

(cream/ointment) or liquid that " X " percent means " X " grams over

100ml (recall 1 cc = 1ml)

Set up a ratio proportion:

2.5 gm........X gm

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

100 ml........8 oz

Because we have `apples', `oranges' and `pineapples ` we can not

cross multiply yet. Not until we make the top (numerators) have the

same units, and the bottom (denominators have the same units).

So let us change (convert) the 8 oz to ml.

1 ounce (dry or liquid)..............8oz

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

30 ml.................................Xml

Cross multiply:

30 x 8

------- = Xml = 240 ml

1

What we now know we can use to substitute into the `original' ratio

proportion set up

>

>

>

2.5 gm.........X gm

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

100 ml.........240 ml

Now we have " apples – apples over oranges - oranges " !!!!

That is reason to go on!

Cross multiply

2.5 gm.........X gm

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

100 ml........240 ml

2.5 x 240

----------- = X gm = 6 gram

100 ml

I do hope this helps you out!

I do need the source of your question please! ( the book it came

from)

Thank you,

Jeaentta Mastron CPhT BSChemistry

Pharm Tech Educator

Founder/owner of this site " "

I do hope this help out a bit, sometimes the internet does not like

to keep things lined up the way we do in on our documents.

Jeanetta

p_silby <p_silby@y...> wrote:hi jeaneatta i have a question that is

stumping me

> What is the total amount of hydrocortisone found in

> eight 1 ounce tubes of hydrocortisone cream 2.5%. The

> answer is 6gm. I can't figure out how they came up with that.

> I've got to be making it harder than it is.

>

> thanks

> Pam

>

>

>

[Guest guest]

OOOOOOOOOOOH! that was much better Jeanetta! Hee!

(self pat on the back! sometimes we have to do it ourselves!

[Guest guest]

Sure the book is Certification review for Pharmacy technicians

sixth edition by Noah Reifman, R.Ph.,MShi jeaneatta i have a question that

is stumping me

> What is the total amount of hydrocortisone found in

> eight 1 ounce tubes of hydrocortisone cream 2.5%. The

> answer is 6gm. I can't figure out how they came up with that.

> I've got to be making it harder than it is.

>

> thanks

> Pam

>

>

>

[Guest guest]

Hi Pam,

Lets see if I can help!

1) what volume of 36% trichloracetic acid solution is needed to prepare

six 2 oz bottles of 10% trichloracetic acid?

There is more than one choice at how to approach this problem. I would look

for the " small " and go " large " - I tend to take things from the " what are

the results " stand point -

so what is it the questions wants :: six 2 oz bottles of 10% trichloracetic

acid

10% will be converted to a metric measure, so I would want to convert my

six 2 oz bottles

1 oz = 30 mL so each 2 oz btl has a volume of 60 mL (we'll deal with the six

factor in a minute)

ok - then 10% :: a percent solution is the amount of drug (in Grams) over

100 mL [this is a solution] = 10 G/100 mL

If there is 10 G/ 100 mL, you want to know how many grams in 60 mL

10 G/ 100 mL = x / 60 mL

(10 G * 60 mL) / 100 mL = x = 6 G

Then you need to determine how many mL of the 36% solution will give you 6 G

of drug.

36% = 36 G/ 100 mL

36 G/ 100 mL = 6 G/ X

X = (6 G*100 mL)/ 36 G = 16.7 mL :: so - each btl will need 16.7 mL of 36%

(diluted to total volume of 60 mL) 16.7 mL * six btl = 100 mL

approach ii:

six 2 oz btl = x mL

6 * 60 mL (see conversion above) = 360 mL of 10% solution

10 G/ 100 mL = x G / 360 mL

x = 36 G (of drug) that is needed from the 36% solution.

36 % = 36 G / 100 mL (hmm - this comes out nice - if you need 36 G and the

solution comes 36 G/100 mL - you see that the answer is 100 mL)

Not all come out this nice - but you see - it doesn't matter which way you

approach the problem - it comes out the same.

2) what formula will produce a 1000 ml solution of 3.5% amino acid in

15% dextrose?

Is there something else in this problem - like the % of amino acid and

Dextrose you are starting with?? Are they both ingredients to be combined for

these %'s or is one the base the other is mixed in???

3.5% = 3.5 G/100 mL

if you are making a 1000 mL bag:: 3.5 G/100 mL = X/ 1000 mL

X = 35 G (you need to know what concentration the original amino acid is to

determine the amount to put into the bag)

15% = 15 G/ 100 mL

15 G/100 mL = Y / 1000 mL

Y = 150 G ( again you need to know the % dextrose you are starting with)

Hope this helps!

Anne P LaVance, BS, CPhT

Instructor

Pharmacy Technician Program

Delgado Community College

New Orleans, LA

TEXTPERT

[Guest guest]

I am having trouble with a couple of questions.

what volume of 36% trichloracetic acid solution is needed to prepare

six 2 oz bottles of 10% trichloracetic acid?

what formula will produce a 1000 ml solution of 3.5% amino acid in

15% dextrose?

I don't know Jeanetta sometimes it seems like I've got it and I take

a step forward then I can't get it and it seems like I've taken 2

steps backwards. I take the exam on the 17th. One day I feel ok

about it and the next day I'm questioning myself. Everyone at work

says I'll do just fine .I've taken the 4 tests in Certification

Review for Pharmacy Technicians and average in the 80's. Not to

mention this site is a lifesaver. Thanks for your help. I could use

some encouraging words from anybody out there.

Pam

[Guest guest]

Dear Pam,

You WILL do just fine! You did not give upon your studying. You ARE

preparing yourself for the exam. It won't matter how many youget

wrong! It will matter how many you get right! The glass is half full

not half empty!

You have much foundation for math and for other information that

will carry you through this exam, and you WILL pass.

Your letter of concern (post) is not unlike the 100's that I have

recieved in my private email and on post in the past. And yet when

allis said and done they too have passed.

I want you to look at the polls of the past! (on this site). Look at

the scores! Then look at the national average of passing rate! 80%

Yet this site has a 100% of those who have responded to the polls.

An there has been NO ONE since 2002 who said that they did not pass,

not even in my private emails!!! That is when the polls began. And

only ONE from 1999 that I know of said they failed, but also stated

that they had only begun studying 2 weeks before the exam!

Your chances are GREAT just because you are here! What does that

mean? Does that mean this site will get you through it? NO! It is

ntothe site it is YOU and YOU alone! The FACT that you are HERE

states volumes of the WORK that you have done to get here and to

where you are going. It says that you had done some study already

and that you had prepared yourself somewhat, and you wanted MORE!!!

That's right YOU WANTED MORE! So that in itself says you WILL PASS.

Now if you do not pass then I expect some honesty from you....to

return to this site and state the reasons why you believe you did

not pass. That will help me and others help YOU and NEW members to

study better for the next exam. But the truth is you WILL PASS,

because you are HERE! And being here means you are PREPARED!

I will address your other issues in a different post.

Love

Jeanetta Mastron CPhT BS Chem

Pharm Tech Educator

Founder/Owner of this site

> I am having trouble with a couple of questions.

>

> what volume of 36% trichloracetic acid solution is needed to

prepare

> six 2 oz bottles of 10% trichloracetic acid?

>

>

> what formula will produce a 1000 ml solution of 3.5% amino acid in

> 15% dextrose?

>

> I don't know Jeanetta sometimes it seems like I've got it and I

take

> a step forward then I can't get it and it seems like I've taken 2

> steps backwards. I take the exam on the 17th. One day I feel ok

> about it and the next day I'm questioning myself. Everyone at work

> says I'll do just fine .I've taken the 4 tests in Certification

> Review for Pharmacy Technicians and average in the 80's. Not to

> mention this site is a lifesaver. Thanks for your help. I could

use

> some encouraging words from anybody out there.

>

> Pam

[Guest guest]

Dear Pam,

I see that my TEXPERT Anne has done this problem during the same

time I was addressing/typing and posting my personal response to

your comments to me regarding your concern of the upcoming exam.

(In the next paragraphs the use of the word " you " is to mean all and

everyone using this site to study and is not directed to Pam solely.)

However I would like to address the same problems from the approach

of the Tutorials that I have placed on this site. Why? Because if

you are using the Tutorials you probably need to see them used, and

I do not wish to confuse you. If you are not using the Tutorials

(you should, they are here and free!)

What is great about Anne and I approaching the problems differently

is that you get two different persectives. As they say " There is

always more than one way to skin a cat " . (Just remmember Iam a cat

lover!)

Anyway…

Problem #1 – A Dilution Problem

" What volume of 36% trichloracetic acid solution is needed to

prepare six 2 oz bottles of 10% trichloracetic acid? "

First of all ANYTIME that I see that I have to make a less strength

solution from another, but stronger solution, I like to use the

Alligation formulas. They are much easier to set up for me. Be sure

to see the Tutorials on this site. Currently the Alligation in the

tutorial uses 30% and 12% instead of the 36% and 10% in your

problem. The only problem with the alligation method is the clarity

of the online posts. The tic tac toe does not always come out nice.

So the tutorial will allow you to see it set up neat and clean

I like to deal with the Quantity I have to make first:

6 bottles of 2 oz of 10 % TCA

6 x 2 oz = 12 oz total of 10% TCA

Now let's change or convert the 12 oz to ml:

Ratio Proportion:

1 0z-----12 oz

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

30 ml-----X ml

Cross Multiply:

30 x 12

--------- = X ml = 360 ml

1

Next Set up an alligation:

To do this we will use water to dilute that has NO TCA in it

therefore it is 0%

---:---: 10

36%:---:---- X 360 ml = 100 ml

---:---:-36

---:---:----

---:10%:----

---:---:----

------------

---:---: 26

0%:---:---- X 360 ml = 260 ml

---:---: 36

Answer: Use 100 ml of 36% TCA and 260 ml of water to make 360ml or

12 oz of 10% Trichloroacetic Acid.

Problem #2 A TPN Base Solution Problem -

" What formula will produce a 1000 ml solution of 3.5% amino acid in

15% dextrose? "

I also agree with Anne that there could be or should be MORE

information to this problem.

However I will give you a problem using the exact same %AA and %

Dextrose required to make a 1L solution containing both:

Rx: Make a 1 L solution using 0.5 L of a 3.5% AA and 0.5 L of 15%

Dextrose

Scenario: You go to the shelf and find only 8.5% AA and D70W in

stock.

There are two approaches that I teach. The C1 x V1 = C2 x V2 and the

Alligation Method. I teach two Alligation Methods or Approaches: the

Double Alligation Method and the Top Only Method:

C1 x V1 = C2 x V2

For the AA

3.5% x 0.5 L = 8.5% x V2

3.5% x 500 mL = 8.5% x V2

3.5% x 500 mL

-------------- = V2 = 205.88 mL or 206 mL of 8.5% AA

8.5%

C1 x V1 = C2 x V2

For the Dextrose:

15% x 0.5 L = 70% x V2

15% x 500 mL = 70% x V2

15% x 500 mL

------------ = V2 = 107.14 mL = 107 mL of Dextrose 70%

70%

Now the total solution is 1L or 1000 ml. So by subtraction we can

find out how much water we need to make the solution.

1000 mL

-206 ml of 8.5% AA

-107 mL of D70W

----------------------

687 mL of Water

Answer: Use 206 mL of 8.5% AA, 107 mL of D70W and 687 mL of Water to

make 1 L of solution.

Double Alligation Method

For AA

----:----: 3.5

8.5%:----:----- X 500 ml = 205.88 or 206 mL

----:----: 8.5

----:----:-----

----:3.5%:-----

----:----:-----

---------------

----:----: 5

0% :----:----- X 500 ml = 294.11 mL = 294 mL Water

----:----: 8.5

For Dextrose:

----:----: 15

70% :----:----- X 500 ml = 107.14 mL or 107 mL

----:----: 70

----:----:-----

----: 15%:-----

----:----:-----

---------------

----:----: 55

0% :----:----- X 500 ml = 382.86 mL = 383 mL Water

----:----: 70

Add the water from each alligation for total amount of water to be

used: 294 mL + 383 mL = 687 mL of Water.

Now let us add this together for a formula:

Answer: Use 206 mL of 8.5% AA, 107 mL of D70W and 687 mL of Water to

make this Rx solution 500ml 3.5% AA and 500 mL of 15% Dextrose.

Another approach to the Double Alligation Method is to use the TOP

Only Alligation Method, in which the set up is the SAME, except do

not do the math of the bottom half of either alligation. Then

subtract the amounts of the two ingredients of the tops of both

alligations from the total amount to be made to find out how much

water is to be used.

1000 ml – 206 mL – 107 mL = 687 mL Water.

Now as soon as you check the math problem in your book, you too can

plug in your percentages in the C1V1 = C2V2 or Double Alligation or

TOP ONLY Alligation Methods.

Okay I hope that one or many of the methods that I and my Texpert(s)

use to approach these math problems will work for you.

Most Respectfully,

Jeanetta Mastron CPhT BS Chemistry

Pharm Tech Educator

Founder/Owner of this site