Anyone Here Good at Math? - Math and Medications

[casportpony]

Here is a good example of the errors:


Let's start with the obvious...


I have no idea how they came up with 1 tablespoon being 2 ounces, and I know for a fact that one tablespoon of that powder does not weigh 15 grams.

-Kathy

 

[casportpony]

Since I've brought this up, let's make it the next exercise.

One bag weighs 181 grams (6.4 ounces)
One bag has 10 grams of tetracycline

Given that info, how many gallons medicated to 800 mg will it make?

-Kathy

 

[Free Spirit]

Powders are tricky, because most people don't have scales and they assume that one tablespoon of powder weighs 15 grams. Di you know that even places like Durvet have made this assumption? Not only have they made that assumption, they have errors in their product catalog.

-Kathy

I have a digital scale that goes up to 11 lbs / 5 kg. I paid $50 US for it and it has come in very handy.

I guess people don't realize that dry weight depends on what is weighed. 1 Tablespoon of salt is heavier than 1 Tablespoon of pepper. Oil is lighter than water at the same measurement.

It doesn't surprise me that Durvet has errors, I see that a lot in various things. I cringe when I see spelling errors in instructions too. Makes you wonder if they have anyone proofreading or has quality control really fallen that far.

 

[casportpony]

Quote: True... Did you know that one tablespoon of table salt weighs more than one tablespoon of water? I haven't confirmed that yet, but did read about it a few weeks ago. With the exception of table salt, I have found that most powders weigh between 9-10 grams per tablespoon.

-Kathy

 

[Free Spirit]

True... Did you know that one tablespoon of table salt weighs more than one tablespoon of water? I haven't confirmed that yet, but did read about it a few weeks ago. With the exception of table salt, I have found that most powders weigh between 9-10 grams per tablespoon.

-Kathy

Because of the density of salt added to the water. Here's a nice Youtube to explain with an example

 

[casportpony]

Quote: It's not just when it added to water... alone it's more than twice as dense, so alone it weighs more than water, too.

-Kathy

 

[Free Spirit]

Here is a good example of the errors:


Let's start with the obvious...


I have no idea how they came up with 1 tablespoon being 2 ounces, and I know for a fact that one tablespoon of that powder does not weigh 15 grams.

-Kathy

If you look carefully between the package measurements and the conversion example. The numbers are transposed (reversed). So it looks like they got it completely backwards. If this is the case then the package directions (when reversing the numbers) should have read:
400mg dose = 1 Tbls (1/2 oz) per gallon of water
800mg dose = 2 Tbls (1 oz) per gallon of water

Not saying this is the case but that's what it looks like from the two examples given.

 

[Free Spirit]

It's not just when it added to water... alone it's more than twice as dense, so alone it weighs more than water, too.

-Kathy

Correct

 

[casportpony]

What would you say if I told you that a few people have counted out number of tablespoons per package?

-Kathy

 

[casportpony]

So if there are 10 grams in the package I like to know how many gallons it will make.

• 10 grams = 10,000 mg, so it's 10,000 / 800 = 12.5 gallons at 800mg

So how many grams per gallon?

• 181 grams / 12.5 = 14.48 grams

This is where it gets tricky... If you don't have a scale you need to find a way to measure out the powder. Several people have done this and the all have measured out abou 18 tablespoons. So what does that mean?

• 181 grams / 18 tablespoons = 10 grams per tablespoon, which is 3.3 grams per teaspoon.

Package weighs 181 grams and has 10 grams tetracycline.
10 ÷ 181 = 0.055, which means it's 5.5% tetracycline, 94.5% filler
One gram = 55mg
One tablespoon weighs about 10 grams which = 550 mg
800 ÷ 550 = 1.45 tablespoons
The 800 mg dose for one gallon = 1.5 tablespoons (825mg is close enough)

Anyway, the dosing info in their brochure is wrong, it just can't be 1 or 2 tablespoons per gallon. Sadly people will continue to give this amount, which might be fine for some bacteria, but maybe not for other bacteria.

-Kathy

Edited to add this:
Tetracycline Powder 5.5% (55mg per gram)

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