Doctor and Bartender by the Numbers

Aug 03 2012 Published by under [Math&Technology]

Last week a piece in the New York Times suggested we should quit teaching algebra because it was difficult to learn and useless.

Useless? Algebra is one of the few things I use regularly, almost daily. Anytime I solve for an unknown value, I am using algebra.

Here is a work example. A baby came in taking 2.5 mL of a 125 mg/5 mL solution of medication. Doing a little math, the dose in milligrams came to 62.5 mg, below the 10 mg/kg we wanted this 8.1 kg baby to receive. How much did we need to increase the dose? Oh, no! It's a classic "word problem" where we have to set up and solve for an unknown value!!!!

81 mg  =  125 mg/5 mL x X mL

Multiply both sides by 5 mL gives us

5 mL x 81 mg  =  125 mg x X mL

Now divide both sides by 125 mg...

3.24 mL = X

So I ended up prescibing 3.5 mL, both to make dosing more practical as well as to accommodate additional growth in the next year.

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Algebraic emergencies...

I get home at night and my husband wants a lemon drop martini. Making two for our extra-large martini glasses requires 1.5 cups of Absolut Citron; I only have 1.25 cups. How much do I need to cut the other ingredients?

1.25 cups  =  1.5 cups x X

Dividing both sides by 1.5 cups...

0.83  =  X

So I multiply the other ingredients by 0.83!

OK, I actually go to the liquor store...but you can see the practical use of the mathematics if this happened on Sunday (Oklahoma blue laws).

I have managed to live a full life with success in medicine and science without ever taking calculus, but I use algebra all the time. I will admit that I have not factored a polynomial since checking my kids' advanced algebra homework, but of all the math I learned, Algebra I has the most practical application. You may not realize it, but you use algebra as well.

For more sophisticated discussions about why this columnist was wrong, see Galactic Interactions and Good Math, Bad Math.

8 responses so far

  • Ryan says:

    Elementary algebra is the use of variables for solving problems. There is no need for variables in the equations you did. You simply used ratios. That's arithmetic. No one argues doctors and bartenders ought to know arithmetic.

  • Krishna Prasad Menon says:

    Algebra can be solved in one or more ways. Even I loved and love algebra most, which I find to be the easiest in mathematics and as rightly mentioned has so many applications and can be applied anywhere. But your second question is not a complete perfect question, the data given does not correspond exactly to your not so intended, vague question, so as to arrive at your answer. The problem can be interpreted in many ways, depending upon the assumption made. But, anyway, exceptional!

  • Pascale says:

    I had a discussion with my son, a sophomore engineering major, about what exactly algebra is. Most definitions include variables standing in for actual numbers and utilizing rules or laws of mathematical relationships. The problems above could be approached using fractions or ratios alone (a subject that in my experience most people find as confusing and frightening as algebra), but in my mind I always solve for the variable as described above.

    This raises the question: What exactly is algebra? Perhaps our math dudes can provide an answer.

  • Krishna Prasad Menon says:

    As to my previous comment on the second question, I would say that your answer is correct, but to arrive at your answer, the question should have been rather straight-forward and simple, rather than making it complicated and misleading with too much of unnecessary data, irrelevant to arrive at your answer. The question, if scrutinized with words and their correlation leads to various interpretations, assumptions and a or may be, other different answers.

  • 1.5 cups of Absolut Citron

    For two motherfucken martinis!?!?!? Jeezus motherfucke, you and your husband now how to fucken drinke!!!

    • Tybo says:

      Exactly, that's what, a 7.5 oz pour? A traditional shot is a 1.5 oz pour. That would be a quintuple martini!

      • Tybo says:

        Nevermind, for some reason I was thinking there were 10 ounces in a cup rather than 8. (Too used to using metric.) Should be 12 oz total, 6 oz each, so a quadruple martini.

  • Glfadkt says:

    Comradde PhysioProffe: I take it that you've never spent any time with Pascale at a scientific meeting (with the associated drinking...)

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