Posts from — November 2005

Yesterday, Mozilla Firefox 1.5 was released… get it here. It has a lot of stuff that’s interesting to nerds, but also some performance improvements, a much-improved method for updating, the ability to move around tabs, and more. I used a release candidate on my laptop and enjoyed it, but I’ll be waiting until it gets into apt.

Also, for anyone who’s interested, a blog I’ve been reading a lot lately is Xooglers, a blog written by a few former google employees. It’s not overly bitter nor overly glossy… just seemingly honest, well-written storytelling and retrospective.

This riddle is pretty neat, I think. Your answer should have some sort of explanation… don’t forget <font color=”white”>…

The overly feminist rulers of a country decide that there are too many baby boys being born. The rulers decide to enforce a new law concerning child birth on their overly prosperous subjects. Each family is permitted to have as many children as they want, provided that they only produce baby girls. Once a baby boy enters the family, the family is no longer permitted to have children. Assuming each law abiding family wants to have as many children as possible, what will happen to the ratio of boys to girls, and why?

A. The ratio of boys to girls will go up.
B. The ratio of boys to girls will stay the same.
C. The ratio of boys to girls will go down.

Ok, the last puzzle was pretty difficult, so tonight’s are easier. Since it’s been a while since I posted, I’m going to provide two.

First, a basic probability question (unlike pretty much everyone else, I like probability):
I flip a penny and a dime and hide the result from you. “A least one of the coins came up heads”, I announce. what is the chance that both coins came up heads?
(this one reminds me of the Monty Hall Problem, which I might post another day)

A bit more challenging, but much easier than last week’s question:
You have 20 coin machines, each of which produce the same kind of coin. You know how much a coin is supposed to weigh. One of the machines is defective, in that every coin it produces weighs 1 ounce less than it is supposed to. You also have an electronic weighing machine. How can you determine which of the 20 machines is defective with only one weighing? (By one use, we mean you put a bunch of stuff on the machine and read a number, and that’s it — you not allowed to accumulate weight onto the machine and watch the numbers ascend, because that’s just like multiple weighings). You are allowed to crank out as many coins from each machine as you like.

Remember to put <font color=”white”> and </font> around any spoilers.

Yesterday when I woke up, there were three inches of snow on the ground. After some second-guessing, I decided to go with my Dad to run in the Manchester Road Race. The course wasn’t all that bad: it was cold (mid 20s) before and after the race, but there wasn’t snow on the road where we were running. I finished with a time of 39:50, just under my 40 minute goal (4.78 miles). Not especially fast, but good enough for such a crowded race and my lack of training. This was the 9th time I’ve run the race, I think (starting in 8th grade, skipping one year).

Thanksgiving was good, as always. Humberto and I made a cheesecake (second attempt) and this time it came out really good. Apparently not leaving it in the oven for an extra 3-4 hours is a good idea.

I’ll post a solution to the latest riddle if nobody gets it soon. If you think you’re close and want to post a partial solution, I can provide pointers.

Today’s riddle is harder than all the others so far… I figure that Thanksgiving break is a good time for it.

You have 12 identical-looking balls. One of these balls has a different weight from all the others. You also have a two-pan balance for comparing weights. Using the balance in the smallest number of times possible, determine which ball has the unique weight, and also determine whether it is heavier or lighter than the others.

Remember to put <font color=”white”> and </font> around any spoilers. I thought I had the answer, but then I found a flaw in my solution, so I need to alter some things. Oh yeah, it can be done in three measurements. Enjoy!

Update: I solved it.

Small Hint/Observation: Each measurement can have THREE outcomes: balanced, left is heavier, or right is heavier. Since there are then 3³ possible sets of events (three measurements with three possibilities each), that means 27 possible events. The number of possible ball and weight selections is 12 * 2 = 24 (since you need to choose one ball and whether it’s lighter or heavier). This means that almost every measurement must have a different outcome based upon all three possibiliites. Not the strongest hint, but it’s important to keep in mind.

Suggested Strategy: You can number the balls and use H and L (heavy and light) to list the possible outcomes each step of the way (1H, 1L, 2H, 2L, 3H, etc). Set up a tree where all 24 possibilities are at the top and after each comparison outcome, list which possibilities remain.

Slightly Bigger Hint: Your last measurement will almost always choose between THREE balls, though it’ll only measure two (not quite always, though).

This one had some challenging questions on it, actually:

You Passed the US Citizenship Test

Congratulations – you got 10 out of 10 correct!

Today’s riddle takes a bit of math to solve (nothing too hard, though). The question doesn’t seem to make much sense at first, but if you do the math all the pieces will come together. Enjoy!

The mother is 21 years older than the child. In 6 years from now, the mother will be 5 times as old as the child. Question: Where’s the father?

A casual reminder:
“All that is necessary for evil to succeed is that good men do nothing.” — Edmund Burke

Just avoiding doing bad things isn’t enough. Too many people don’t keep this in mind, myself included, and it’s absolutely disappointing.

In other news: this has been my latest night in many months, and a very enjoyable one.

As many have noticed, AOL decided to add “ShoppingBuddy” and “MovieFone” to buddy lists. I decided to talk with my new friend…

(10:49:42) Me: WILL YOU BE MY BUDDY?
(10:49:43) ShoppingBuddy: Welcome. Now you can search for products with AOLShopping. Type main to get started. To read our privacy policy, type privacy anytime.

(10:49:47) Me: I HAVE NO FRIENDS
(10:49:47) ShoppingBuddy: OK, I’m searching for matches 4 U. Gimme a sec…

(10:49:47) ShoppingBuddy:
- Search results for FRIENDS

- Sweet Fifteen [$5.48 - $9.95]
- Violence, Nudity, Adult Content [$5.15 - $14.07]
- Red Lily [$6.54 - $33.99]
- The Bean Trees [$1.49 - $19.95]
- I Love You Like a Tomato [$4.76 - $6.99]
- Little Earthquakes [$10.93 - $35.21]
- Some Things I Never Thought I’d D [$5.65 - $89.95]
- Where Do We Go from Here? [$10.41 - $24.95]
- One True Thing [$1.49 - $14.00]

Here are some related categories: 1. Family & Friendship Books, 2. Books & Magazines, etc. Type in the number to use the related category.

(10:49:59) Me: YOU ARE THE ONLY PERSON I CAN TALK TO
(10:49:59) ShoppingBuddy: OK, I’m searching for matches 4 U. Gimme a sec…

(10:50:00) ShoppingBuddy:
- Search results for PERSON TALK

- Salesmanship In A Nutshell : 45 y [$9.99]
- Among Friends [$4.75]
- Talk About Trouble A New Deal Por [$15.00]
- The Talk Of The Town [$5.99 - $11.99]
- The de-Voicing of Society: Why We [$2.50]
- Why We Don’t Talk To Each Other A [$16.56]

Here are some related categories: 1. Miscellaneous Books, 2. Jazz Instrumental Music, 3. Books & Magazines, 4. Music, etc. Type in the number to use the related category.

(10:50:14) Me: I THINK I’M GOING TO KILL MYSELF
(10:50:14) ShoppingBuddy: OK, I’m searching for matches 4 U. Gimme a sec…

(10:50:17) ShoppingBuddy:
- Search results for THINK GOING KILL

- Help, I Think God is Trying to Ki [$10.39]
- UpRoot™ Lawn Weeder [$36.50]

Here are some related categories: 1. Miscellaneous Books, 2. Garden Tools, 3. Books & Magazines, 4. Home & Garden, etc. Type in the number to use the related category.

(10:50:23) Me: YOU JUST KEEP GIVING ME SHOPPING THINGS, I NEED HELP!
(10:50:23) ShoppingBuddy: OK. Who are you still shopping for?

1 — Myself
2 — Someone Else

(10:50:54) Me: NO, FOR THE LOVE OF GOD, I JUST NEED TO TALK
(10:50:54) ShoppingBuddy: Ok, so which category do you need?

1 – Men’s
2 – Women’s
3 – Boy’s
4 – Girl’s
5 – Babies

(10:52:20) Me: THERE’S BLOOD EVERYWHERE
(10:52:20) ShoppingBuddy: I didn’t find what you were searching for in the GAP HOLIDAY FAVORITES. Would you like me to search AOL Shopping?

Y – Yes
N – No

For more GAP gift suggestions go to gap.com.

Tonight’s riddle is a bit more challenging, but certainly doable.

Using only a 5-gallon bucket and a 3-gallon bucket, put exactly four gallons of water in the 5-gallon bucket. (Assume you have an infinite supply of water. No measurement markings on the buckets.)

Enjoy!

Side note: I wonder what an algorithm to solve this sort of problem (given any number of buckets of different sizes, etc) would look like. What would its complexity be? Maybe I need to stop reading these papers..