Calculation Question... PLEASE help!!

[pharm00123]

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This is from the SDN 120 math questions.. for some reason its just not clicking for me. Specifically its number 9 and 10.

You need to prepare a 30 g of a 0.25% triamcinolone in cold crea. Triamcinolone is available in a suspension of 40 mg per ml that has a specific gravity of 1.

9. How many ml of triamcinolone solution will be needed?
10. How many grams of the cold cream will be needed?

Anyone that helps I would appreciate it SOOO much! Please and thank you! 🙂

 

[anomaly285]

30g x .25% = 0.075g Triamcinolone

9) 0.075g x ml/0.04g = 1.875ml Triamcinolone

Since Spec Grav is 1, 1ml = 1 g, so above = 1.875g Triamcinolone

10) 30g -1.875g = 28.125g Cold Cream

 

[pharm00123]

30g x .25% = 0.075g Triamcinolone

9) 0.075g x ml/0.04g = 1.875ml Triamcinolone

Since Spec Grav is 1, 1ml = 1 g, so above = 1.875g Triamcinolone

10) 30g -1.875g = 28.125g Cold Cream

I am still a little confused on this problem.. I keep wanting to do 0.25%=0.25g/100ml * 30 g = 12,000ml what am I doing wrong?? How can you multiply .25 % by 30 and get .0075g??? Can someone please help?

 

[edalg]

I am still a little confused on this problem.. I keep wanting to do 0.25%=0.25g/100ml * 30 g = 12,000ml what am I doing wrong?? How can you multiply .25 % by 30 and get .0075g??? Can someone please help?

Double clear your calculator, because you must have some value in memory that's changing your answer when you multiple those numbers. Anomaly solved it correctly.

PS - I played with some numbers to figure out what you're doing wrong. You're dividing 100/0.25 and you're getting 400*30 = 12000. That's where your mistake is at.

 

[newlearner2014]

I am still a little confused on this problem.. I keep wanting to do 0.25%=0.25g/100ml * 30 g = 12,000ml what am I doing wrong??

How can you multiply .25 % by 30 and get .0075g??

Can someone please help?

Allow me to explain the line of anomaly285 :
“30g x .25% = 0.075g Triamcinolone”

Here is the reasoning of that line:
In final product, you have creamy mixture:
0.25% = means: (0.25 grams of TRIAMCINOLONE CHEMICAL) / (100 grams of MIXED cream)

We need to setup the links:

I have (0.25 grams of TRIAMCINOLONE CHEMICAL) in (100 grams of MIXED CREAM).
I have (x grams of TRIAMCINOLONE CHEMICAL) in (30 grams of MIXED CREAM)?

x = ((0.25 grams of TRIAMCINOLONE) TIMES (30 grams of MIXED CREAM)) THEN DIVIDE BY (100 grams of MIXED CREAM)) = 0.075 grams of TRIAMCINOLONE.

This means:
Because I have (0.25 grams of TRIAMCINOLONE CHEMICAL) in (100 grams of MIXED CREAM).
Which will mean:
I have (0.075 grams of TRIAMCINOLONE CHEMICAL) in (30 grams of MIXED CREAM).

Then, we can continue with the rest of anomaly285

9) 0.075g x ml/0.04g = 1.875ml Triamcinolone

Since Spec Grav is 1, 1ml = 1 g, so above = 1.875g Triamcinolone

10) 30g -1.875g = 28.125g Cold Cream


To avoid confusion, please try to setup the links like below:
You will see clearly 3 factors out of 4. Base on 3 factors, you will get factor number 4 easily without confusion.

Example of the way to setup links:
I have (0.25 grams of TRIAMCINOLONE CHEMICAL) in (100 grams of MIXED CREAM).
I have (x grams of TRIAMCINOLONE CHEMICAL) in (30 grams of MIXED CREAM)?

Cheers !!!