Skip to main content

Household mathematics

I have figured out why I hate folding socks---it's a simple problem of mathematics.

7 days x 2 feet x 5 people = 70 socks---not counting all the times that Amanda loses her socks between outings and needs a new pair.

The total number of possible pairs of socks is 70x69/2=2415. Given a random sock pick, the chance that you pick out the pair for that sock is 1 in 69. Once you've got that pair, the chance you pick out a pair on the next two grabs is 1/67... Assignment: what is the chance that, reaching randomly into the bin each time, you come up with exactly the right pairing of socks?

If I had the time and no toddler, I could figure out the average time it would take you to pair up all the socks (someone has surely already done this). This doesn't even take into account all the lone socks that simply have no mate, no matter how many times you reach into the bin.

I realize that in real life the grabs are not random (you won't accidentally grab Eleanor's purple sock when you are looking for Mama's black sock). I have also made the problem easier by not sorting any of Michael's socks: I put them all in a drawer and he sorts them as he puts them on. I realize that I could also make this easier by buying all one kind of sock for each person: all purple for Eleanor, all pink for Amanda, etc. I'm not ready to do that yet (socks have been the one place I have felt free to express myself in clothing), but after thinking about the mathematics, I'm taking it under advisement.
Labels:

Comments

Anonymous said…
Well, perhaps when Luke is 5 he will opt to wear the same socks for days in a row like my kid does. Gross, but it does cut down on laundry...

FNDP
January 29, 2009 at 6:30 AM
mathmom said…
FNDP: One can only hope =)
January 29, 2009 at 8:31 AM
Post a Comment

Popular posts from this blog

Why you should study the history of math

  Why you should study the history of math In the mid 1300s a fad made its way around Italy. Mathematicians would challenge each other to “mathematical duels”. They would post problems for their opponents to solve, sometimes along with their solutions in coded poetry. The winners would get support and funding from rich patrons, the losers would descend into obscurity. One such contest, between Fiore and Tartaglia, involved a new method for solving the cubic. In order to win, Tartaglia worked day and night to find Fiore’s method---unfortunately, Fiore did not do the same and only knew his own method and no others. (*Recall that the formula for solutions to quadratic equations of the form use the quadratic formula, Giorlamo Cardano---physician, philosopher, astrologer and mathematician---convinced Tartaglia to share his method and promised never to reveal it. Then Cardano figured out a more general method, and wanted to share it, but was blocked by his promises. Fortunately (for Cardan
Post a Comment
Read more

Southern butter mints---vegan edition

After the last post, we started to be able to see what the fuss was about.  The ones made with twice the butter were the best candy I have ever tasted.  Ever.  So then we started experimenting.  How long do you pull it?  Longer than you think.  And then pull a minute or two after that.  Suddenly every single batch was creaming, pretty much right after we would cut them. I tried adding less than double butter and I think they taste much better (more delicate, according to one taste tester). The latest experiment we did involved using Earth Balance instead of butter.  It cooked pretty much the same as usual, although I was distracted right at the moment I had to pull it off the stove so it cooked maybe a bit longer than usual.  Amanda and I each pulled a quarter, while Luke pulled the bigger half.  Luke's really wasn't turning very fast---perhaps because it was too hot when he took it off the marble.  Mine was turning faster than Amanda's so we traded for a while.  Aman
Post a Comment
Read more

Parenting successes?

Chanson at Letters from a Broad has a post which includes of one of her parenting successes , involving the benedictory smile of a Swiss cashier. I've had some of those public recognitions of good parenting, and I always try to point out to parents when their kids are doing particularly well (especially when the parents look harried). Sometimes, though, the success doesn't look like a success to outsiders. Last week we took the kids to our favorite Greek restaurant. We have been getting gyros for Amanda for a few years now (dairy, egg and nut free!), and we have typically gotten one plate of gyros for Amanda and Luke to share. We get it with french fries, and Amanda is "rewarded" for eating the meat by getting to eat as many french fries as she can (she needs all the calories she can get). Luke's idea, smart boy that he is, is that he doesn't need to eat anything other than the french fries. This week we had had enough of this, and instead of letting Luke
2 comments
Read more