Confused about a dimensional analysis question

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I am not yet a nursing student, but I am required to know some basic dosage calculations for the nursing entrance exam. So I am working through a dosage calculations book. I have come across a situation twice now that I don't understand, and my husband who is very smart in math doesn't understand either.

Here is the question:

8 fl dr = How many fl oz?

I looked at the conversions I have to work with and chose, 1oz(8dr) = 30ml. I arranged my problem and came up with the answer of 1 fl oz and my husband came up with the same answer. However, the answer in the book works the problem using 5ml = 1dr and 1oz = 30ml and they get the answer 1.3 fl oz.

This is a problem that I have encountered twice now - how am I suppose to know which conversion to use? They aren't completely accurate.

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Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

I know that 8fl dr is = to 1fl oz. The apothecary system isn't really used at all anymore..(I haven't seen it in 30 years)..I have NO CLUE why nursing school teach it except to drive students crazy and to drive home the math.

However they are doing the calculation that 1fl dr is = to 0.13oz. Which is actually 1.04....so where they are getting 1.3.....I have NO CLUE!

They are wrong the workbook is wrong.

Anyone else?

ps....great site....http://www.dosagehelp.com/

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Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

conversions and check out this thread......https://allnurses.com/nursing-student-assistance/how-convert-drams-741698-page2.html

The Short List 1 cup © = 8 ounces (oz)

1 dram (dr) = 60 grains (gr)

1 dram (fl dr) = 60 minims

1 gallon (gal) = 4 quarts (qt)

1 glass = 8 ounces (oz)

1 grain (gr) = 64.8 milligrams (mg)

1 gram (g) = 15.43 grains (gr)

1 inch (in) = 2.54 centimeters (cm)

1 kilogram (kg) = 2.2 pounds (lb)

1 liter (L) = 1.057 quarts (qt)

1 milliliter (mL) = 16.23 minims

1 minim = 1 drop (gt)

1 ounce (oz) = 2 tablespoons (tbsp)

1 ounce (oz) = 8 drams (dr)

1 ounce (fl oz) = 29.57 milliliters (mL)

1 pint (pt) = 16 ounces (oz)

1 pound (lb) = 16 ounces (oz)

1 quart (qt) = 0.946 liters (L)

1 quart (qt) = 2 pints (pt)

1 tablespoon (tbsp) = 3 teaspoons (tsp)

1 teacup = 6 ounces (oz)

1 teaspoon (tsp) = 4.93 mL

The Long list

1 central = 45,359 grams (g)

1 centimeter (cm) = 10 millimeters (mm)

1 cubic centimeter (cc) = 1 milliliter (mL)

1 cup © = 8 ounces (oz)

1 drachm = 3.55 milliliter (mL)

1 dram (dr) = 60 grains (gr)

1 dram (fl dr) = 60 minims

1 gallon (gal) = 4 quarts (qt)

1 gill = 4 ounces (oz)

1 glass = 8 ounces (oz)

1 grain (gr) = 64.8 milligrams (mg)

1 gram (g) = 1,000 milligrams (mg)

1 gram (g) = 1,000,000 micrograms (mcg)

1 gram (g) = 15.43 grains (gr)

1 hand = 4 inches (in)

1 inch (in) = 2.54 centimeters (cm)

1 kilogram (kg) = 1,000 grams (g)

1 kilogram (kg) = 2.2 pounds (lb)

1 liter (L) = 1000 milliliters (mL)

1 liter (L) = 1.057 quarts (qt)

1 meter (m) = 1,000 millimeters (mm)

1 meter (m) = 100 centimeters (cm)

1 milligram (mg) = 1,000 micrograms (mcg)

1 milliliter (mL) = 1 cubic centimeter (cc)

1 milliliter (mL) = 15 drops (gt)

1 milliliter (mL) = 16.23 minims

1 minim = 1 drop (gt)

1 ounce (fl oz) = 2 tablespoons (tbsp)

1 ounce (oz) = 20 pennyweights (dwt)

1 ounce (oz) = 24 scruples

1 ounce (oz) = 31.1 grams (g)

1 ounce (oz) = 480 grains (gr)

1 ounce (oz) = 8 drams (dr)

1 ounce, fluid (fl oz) = 29.57 milliliters (mL)

1 palm = 3 inches (in)

1 pennyweight (dwt) = 24 grains (gr)

1 pint (pt) = 16 ounces (oz)

1 pint (pt) = 4 gills

1 pound (lb) = 16 ounces (oz)

1 pound (lb) = 350 scruples

1 quart (qt) = 0.946 liters (L)

1 quart (qt) = 2 pints (pt)

1 scruple = 20 grains (gr)

1 stone = 0.14 cents

1 tablespoon (tbsp) = 3 teaspoons (tsp)

1 teacup = 6 ounces (oz)

1 teaspoon (tsp) = 60 drops (gtt)

1 teaspoon (tsp) = 4.93 mL

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Ok, thank you - maybe I don't have a good book because this has happened twice now. I will check out that site you posted! I just need to know some very basic dosage calculations for my pre-entrance exam, so I am not even going to worry about drams.

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Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

Yeah they are really outdated but some schools will throw them in just to make students crazy.

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Specializes in Hospice.
Ok, thank you - maybe I don't have a good book because this has happened twice now. I will check out that site you posted! I just need to know some very basic dosage calculations for my pre-entrance exam, so I am not even going to worry about drams.

I took Dosage and Calculations and the book was fine. I took Math for Allied Health and the book was so full of errors that even the instructor didn't know the answers half the time. I got an A in that class but I have no idea how anyone even passed considering how confusing the book was. All I can say is my dosage and calculations class must've prepared me well to pass Math for Allied Health. One thing that I wish were different is that I prefer the ration proportion method to dimensional analysis but according to my school they want us to know dimensional analysis instead. I guess it's more accurate and precise.

Up Vote Up Vote ×
Specializes in Hospice.
I know that 8fl dr is = to 1fl oz. The apothecary system isn't really used at all anymore..(I haven't seen it in 30 years)..I have NO CLUE why nursing school teach it except to drive students crazy and to drive home the math.

However they are doing the calculation that 1fl dr is = to 0.13oz. Which is actually 1.04....so where they are getting 1.3.....I have NO CLUE!

They are wrong the workbook is wrong.

Anyone else?

ps....great site....DosageHelp.com - Helping Nursing Students Learn Dosage Calculations

Thanks for that link! Bookmarked it on my computer.

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