bonanova

They're fairly common now. But back in the '60s, when they were introduced, photochromic sunglasses - they turned dark in bright sunlight - made a bit of a splash. Materials that behaved like that were quite uncommon. But some bloke did the research and came up with the following, rather amazing, piece of information. Photochromic materials are reportedly several millenia old, dating to the time of Alexander the Great. This is a summary of a piece that appeared in 1966 in the IEEE Spectrum technical magazine. What you're about to read may astound you. Most people think of photochromic materials as a recent invention. But records indicate that this is not so. It is recorded that the soldiers of Alexander the Great knew of a black substance which could be ground into a powder, dissolved in water and then soaked into swatches of cloth torn from their uniforms. When tied around a soldier's wrist, and as the sun rose, then sat high in the sky, and later set in the West, the cloth would change colors in a subtle way. With practice, the unaided eye could discern these color changes and from them deduce quickly the approximate time of day. That invention became widely known as Alexander's Rag Time Band.

A closer reading of the OP reveals that ... ... normdeplume's answer does meet the criteria.

Storm: Pauli's exclusion principle? Pauli was a snake? The Turtle Girl: Answer: the same as the number of shepherds it takes to make a shepherd's pie.

I drew and labeled a 15x15 grid. Then it took Nice puzzle.

The OP was a double-header: a puzzle and a consciousness raiser. Kudos. The puzzle part teaches that you need a test that has at least an order of magnitude better accuracy than the needle in a haystack that you're looking for. If, that is, you are going to rely on a single test. The puzzle made them equal [1% offenders and 1% error rate] so the results ended up a coin toss. Thus it was noted, if you're working under those statistical conditions, your strategy must include retesting. [Not to quibble over terminology.] Testing strategies undoubtedly vary among the organizations that employ them. Some do a worse job than others. It's a reach, however, to throw out screenings, solely on that basis. Also noted, if you can't reduce the false positive rate, then enriching the population is indicated -something that retesting accomplishes. On these points, Major League Baseball's Drug Policy and Prevention Program is an interesting case to examine. Recognizing that better accuracy may be bought at higher cost, MLB employs a two-tiered test analysis strategy: a more economical and speedier one for screening, followed by a more accurate and costly definitive test on the positive screen results. Here's an excerpt from Section 6. Laboratories: If the screening test gives a presumptive positive result, the drug's presence must be confirmed by a second definitive test using the gas chromatography/mass spectrometry (GC/MS) technique. Regarding the consequences of an initial positive test, MLB does not "rush to judgment," either, as seen from this excerpt from Section 7. Discipline: An initial positive test result, the admission of drug use or the identification of drug use through other means will not immediately result in discipline for the player of Baseball personnel involved other than being required to participate in Baseball's testing program. Again, enriching the test population. This strategy could serve as a model for other organizations. Bottom line: know what you're doing, but then go ahead. Kudos to Topher for a great post.

Can you make this two separate sentences? "no card ... starts or ends with two jokers" doesn't make sense.

The league should retest all the positives.

Now I've read Elightened's post. He has a better answer. In fact, following his reasoning the puzzle could be made a lot tougher: Two grandmothers, two grandfathers, two grandsons, two granddaughters, two great grandsons, two great granddaughters, etc...

Seven.

N, T

Read the original post.

Kudos to EventHorizon for getting it first.

Not within the parameters of the puzzle.

Read the last line of the OP - this is a different puzzle.

[1] Eureka is always good; displacement seems irrelevant. The method is up to you; the OP just asks for the answer. [2] If you saw the lady, you might become interested. It's entirely up to her; have at it, and good luck.

Good one.

Since the puzzle mentions a spare tire, that's probably the solution. However, if the trunk was airtight, causing death by asphyxiation to the other, it's problematical that the air in a single tire could have enabled the first guy to survive. Even a scuba tank couldn't have lasted all night.

The OP is not clear about who wrote the original paper. The action of the "guy" was to have Jacques translate the paper; for that, he wanted to credit Jacques. Reasonably, then, the credits were written [in English] after the translation. The credits then needed to be translated; and that required the additional credits. Make sense?

I did the iteration by hand using an interpretive program - took only about 10 iterations. You can also use Newton-Raphson method to get convergence in 3-4 iterations given a good 1st guess. Didn't feel like being that elegant. This is not cheating by the way -- don't feel guilty about going this route. It's very legitimate numerical analysis technique. If the equations were transcendental, you couldn't arrive at a closed form solution. Numerical methods would be all that you had. Sure. Only two of the three are physically realizable. Whether "solution" refers to the puzzle or to the equations is up for grabs, but if it's the former there are only two. If I had drawn the third line, it would have started on the upper right corner then gone to the ground to the left of the picture, passing through the pole at 8.65... feet. That would have satisfied the equations I set up, but not the actual conditions of the puzzle.

Judging from the discussion in the first few posts, the flagpole is on one corner of the building. It then falls diagonally toward the building so that the broken part passed directly above the center of the roof.

[1] Axis of drill passes through center of sphere. And out the other side, of course [2] Yes you can.

Exactly. I might have been playing with semantics...