Joho the Blog » puzzles

February 20, 2013

How many birds are killed by cats? How many people subscribe to the Boston Globe online?

How many birds do domestic cats in the United States kill every year? You win if your answer is within an order of magnitude in either direction. However, you don’t actually win anything.

The answer comes from the journal Nature Communications as reported here

To reveal the answer, select the black box. (This assumes you don’t have black set as your selection color.)

“We estimate that free-ranging domestic cats kill 1.4 to 3.7 billion birds and 6.9 to 20.7 billion mammals annually.”

And now for extra credit, within an order of magnitude, how many people subscribe to the online version of the Boston Globe? Hint: It costs $3.99/week. Hint: Greater Boston’s population is about 4M. Hint: This quarter, online subscriptions rose 8%. (The answer comes from an article at BizOnline.)

28,000

By the way, I occasionally like to acknowledge that the “order of magnitude puzzle” was invented by my famous friend Paul English.

9 Comments »

November 14, 2012

Daily [Intermittent] Open-Ended Puzzle: Camera shutters

Why do digital SLR (single lens reflex) cameras have shutters?

In analog days, the shutter let light in for some determinant time. That caused the film to be exposed for that duration. But in the digital age, why doesn’t “setting the shutter speed” just tell the internal computer how long it should record data from the sensor? What good does it do to actually open and close a physical shutter?

Just curious. And probably misinformed.

3 Comments »

January 11, 2012

Order of magnitude puzzle: Android sign-ins

One of the security options with Android lets you sign in by dragging you finger to trace a pattern you’ve chosen on a 3×3 square numbered 1-9. The codes have to be at least 4 digits long, you can’t repeat any digit, and you can’t lift your finger off the pad. To my always-wrong intuition, that seems like it affords too few possibilities. So, your task is to guess (or, if you must, figure out) roughly how many choices there are.

[Semi-Spoilers] You start with with the following range of numbers: 1,234 to 987,654,321. That is a boatload of numbers. But you remove all the numbers that have repeated digits. For a 9-digit number, there are only 362,880 numbers (9 factorial) without repeated digits, so that’s like subtracting 100 million numbers from the mix. Our son Nathan says that it’s the same number for all the 8-digit possibilities, because 8 factorial x 9 is the same same as 9 factorial. (I’m lost. Ask him.) After you do all of them down through 4-digits, you have to subtract the sequences that have non-contiguous numbers (based on the 3×3 square). So, it’s a big number, especially since the Android UI puts in a time-out after 10 wrong tries. But it’s not an astronomical number. I’m guessing it’s under a million.

But I fully expect to be shown to be wildly wrong.

3 Comments »

March 22, 2011

[doep] Daily (intermittent) Open-Ended Puzzle: Why do moths fly the way they do?

My understanding (possibly bogus) is that moths spiral into flames because evolution has designed them to fly in straight lines by noting celestial lights. When the light is nearby, keeping its position fixed in their visual space causes them to spiral inward toward it.

Fine. But why is it an evolutionary advantage for moths to fly in a straight line? Where are they trying to get to so quickly? And isn’t there a metaphor for MBAs somewhere in here?

1 Comment »

March 6, 2011

[doep] Daily (Intermittent) Open-Ended Puzzle: Dig a hole…

The following is an Order of Magnitude puzzle: Guess within an order of magnitude of the answer and you win! You win nothing!

If you were to start any spot on land on Earth and dig a hole through the center of the Earth, what percent of the time would you come out on another spot on land, as opposed to having water spray out, comically spinning the Earth out of orbit to its death? (To be precise, the question isn’t about water spraying or not spraying out of the hole. It’s about the percentage of times you’d hit land.)

The answer is in the comments. But, wait, to help you, this fabulous mashup using the Google Maps API will let you sink your own knitting needles through the Earth’s nougaty core!

(All of this came from a mailing list I’m not supposed to acknowledge. Answers authenticated by the good folks at Wikipedia.)

2 Comments »

April 2, 2010

Deep thoughts (alphabetical)

If Hollywood put up a big “Marilyn Monroe” sign, it would make sense for you to say that you snuck up there last night and switched the “M’s.”

If you type the name “Marilyn Monroe” and then copy and drag the M’s to transpose them, we would agree that you switched the M’s … but when you save the file and reopen it, are the M’s are still switched?

25 Comments »

February 20, 2010

Order of Magnitude Quiz: Patents

How many patents do you think there are in the United States? (I believe that the number that I have, which comes from Beth Noveck’s excellent Wiki Government, refers to the number of patents in effect.)

Because this is an Order of Magnitude quiz, you win if your answer is within one order of magnitude of the right answer.

The right answer is in the first comment.

Note: Winning means that you win nothing. Just to be clear.

4 Comments »

February 2, 2010

The Data-Info-Knowledge-Wisdom hierarchy

As part of my Be A Bigger A-Hole resolution, let me note that the Harvard Business Review blog has just run a post of mine that looks at the history of the DIKW pyramid and why it doesn’t make that much sense.

5 Comments »

November 8, 2009

Order of Magnitude Quiz: How many travelers

According to the Boston Globe, how many travelers fly in or out of Boston’s Logan Airport every year?

You win this quiz (and get exactly nothing as a prize) if your answer is within an order of magnitude of the right answer. (And I should periodically acknowledge that my friend Paul English invented the Order of Magnitude Quiz.)

The answer is in the first comment.

5 Comments »

September 19, 2009

Order of Magnitude Puzzle: Bees per gallon

You win an Order of Magnitude puzzle if your answer is within an order of magnitude of the right answer. On the other hand, you don’t actually win anything. So, here goes:

How many bees do you think are in a pound? (And isn’t the answer none if they’re all flying?)

How many bees per gallon?

The answer is in the comments. (Note: This is not a computation WolframAlpha can help you with.)

3 Comments »