06 April 2006

Math makes me cry

Not because I can't do it, but because others can't.

To get a 5 percent solution from 80-proof liquor, which is 40 percent alcohol, add one part liquor to seven parts water.


That needed to be explicitly stated? Sad.


utenzi said...

Not everyone has the same skills, ZP. I know that's obvious but you need to keep it in mind. The "problem" that you quoted from CNN isn't obvious to most people. It's shocking how many people think that taking a 20% discount from an item already marked down 30% makes it 50% off. I've had to explain to students what that isn't the case and many of them never got it.

I'd say that the inability to calculate molarity is the biggest problem I have with summer research students. This is really scary since many of them are medical students between their second and third year. These folk are about to be prescribing aqueous meds that are based on % strength and molarity!

zandperl said...

Actually, I have to admit that I find moles, Avogadro's number, and molarity very difficult. It seems counter intuitive to me, and I'm used to dealing instead with things like numbers, number density, mass density, and so on.

To me the atomic mass unit isn't something to do with moles, but a non-SI unit of mass much like the pound (well, slug technically). I know the amu comes from something, just like the AU, lightyear, and parsec come from things, but there's no reason for me to use that derivation so the concept of moles is meaningless to me. :-P

Number density took me quite a while to grok too, but that *is* used in astronomy, so I figured it out and it's now intuitive.