# Logic Quiz

1. Jan 28, 2006

### Staff: Mentor

Answer in white. I will post the answers after enough people have a chance to play. There are some interesting discussion notes with the answers.

I'll award 5 points per correct answer since we may not have anyone get them all correct.

1. Cathy has six pairs of black gloves and six pairs of brown gloves in her drawer. In complete darkness, how many gloves must she take from the drawer in order to be sure to get a pair that match? Think carefully!!

2. Mom, Dad, and 2 kids have come to a river, and they find a boat. It is small and can only carry one adult or 2 kids at a time. Both kids are good rowers, but how can the whole family reach the other side of the river?

3. Why can't you take a picture of a Indian woman with hair curlers?

4. What is the largest possible number you can write using only 2 digits - just 2 digits, nothing else?

5. Before Mt. Everest was discovered, what was the tallest mountain in the world?

6. Because cigars cannot be entirely smoked, a hobo who collects cigar butts can make a cigar to smoke out of every 5 butts that he finds. Today, he has collected 25 cigar butts. How many cigars will he be able to smoke?

7. Jenn is facetious. She is also abstemious. She gets pneumonia. Given those clues, what is the only American tree she will like?

8. How many birth days does the average man have?

9. Someone at a party introduces you to your mother's only sister's husband's sister in law. He has no brothers. What do you call this lady?

10. Which weighs more, a pound of feathers or a pound of gold?

11. Two planes take off at the same exact moment. They are flying across the Atlantic. One leaves New York and is flying to Paris at 500 miles per hour. The other leaves Paris and is flying to New York at only 450 miles per hour ( because of a strong head wind ). Which one will be closer to Paris when they meet?

12. A carpenter was in a terrible hurry. He had to work as quickly as possible to cut a very heavy 10 foot plank into 10 equal sections. If it takes 1 minute per cut, how long will it take him to get the 10 equal pieces?

13. Why are 1898 silver dollars worth more than 1897 silver dollars?

14. What English word can have 4 of its 5 letters removed and still retain it's original pronunciation?

15. Johnny's mother had three children. The first child was named April. The second child was named May. What was the third child's name?

16. In your sock drawer, you have a ratio of 5 pairs of blue socks, 4 pairs of brown socks, and 6 pairs of black socks. In complete darkness, how many socks would you need to pull out to get a matching pair of the same color?

17. How can a woman living in New Jersey, legally marry 3 men, without ever getting a divorce, be widowed, or becoming legally separated?

18. A woman goes into a hardware store to buy something for her house. When asked the price, the clerk replies, "the price of one is twelve cents, the price of forty-four is twenty-four cents, and the price a hundred and forty-four is thirty-six cents. What does the woman want to buy?

19. If there are 5 apples on the counter and you take away 2, how many do you have?

20. If, having only one match, on a freezing winter day, you entered a room which contained a lamp, a kerosene heater, and a wood burning stove, which should you light first.

Last edited: Jan 28, 2006
2. Jan 28, 2006

### mattmns

1. 3
2. Both kids go over, one comes back, one adult goes over, the other kid comes back, both kids go over, one comes back, the other adult goes over, the kid comes back, and both kids go over
3. How would you take a picture using hair curlers?
4. 98?
5. Mount Everest
6. 6
8. 1
10 they weigh the same?
12. 9 minutes
15. Johnny
16. 4
19. 5

Whew, I got some easy ones out of the way

Ok I did a few more, somebody else needs to post, before I figure them all out

Last edited: Jan 28, 2006
3. Jan 28, 2006

### sporkstorms

13 total. 6 left gloves, 7 right (or vice versa)

Swim ;)

I've never seen hair curlers with lenses, an aperture, etc. It'd probably be easier with a camera.

Without cheating and trying to argue that infinity is a digit, 9^9

If a tree falls in the forest and nobody is around to hear it, does it make a sound? Yes, and Mt Everest was still the tallest before anyone found it

Just one.

Mom

2, unless they were somebody else's and the kicked me in the stomach and took them back.

Well, none of the others would do much good unless you lit the match first ;)

Last edited by a moderator: Jan 28, 2006
4. Jan 28, 2006

### Staff: Mentor

spork, I said WHITE. :grumpy:

5. Jan 28, 2006

### Orefa

Trying COLOR="#E9E9E9" instead of white (it still shows a bit on my screen).

1. Eight: one left glove and seven right gloves (or vice versa). One of the right gloves will match the color of the left one.

2. 2 kids across, 1 kid back. Mom across, other kid back. Repeat for the dad, then 2 kids across to finish.

3. Hair curlers don't take pictures.

4. 9 to the power of 9.

5. Mt Everest.

6. 6.

7. No idea. Had to look up "abstemious"...

8. One.

9. Mom.

10. Hey, a pound is a pound.

11. They meet at the same position.

12. Nine cuts, nine minutes; less if he can cut creatively.

13. There's one more dollar.

14. Hmmm. Can only think of... nothing. Pass.

15. Johnny.

16. With luck, only 2. To be sure, 4.

17. Are annulments allowed?

18. Street numbers (for her house address) at 12 cents per digit.

20. The match!

6. Jan 28, 2006

### sporkstorms

Sorry. But, the default background on the forum is grey.

Anyhow, nice topic. Interesting questions :)

7. Jan 28, 2006

### sporkstorms

That's even better. It doesn't show up at all for me (in Safari).

By the way, good answer on the gloves question. I was on the right track, but just didn't think it all the way through.

8. Jan 28, 2006

### Staff: Mentor

Yeah, since the skin color changed, nothing is truly invisible anymore.

I can't take credit for it, I'll be posting a link to the quiz site after we finish.

9. Jan 29, 2006

### Gale

which ones aren't done yet?

10. Jan 29, 2006

### Staff: Mentor

Do any you have answers to because not all of the answers so far are correct. You'll get 5 points per correct answer and we'll tally who has the most correct answers at the end.

11. Jan 29, 2006

### rachmaninoff

People! White colors do not work anymore if you're trying to hide text! Use color=#ececec.

Here I go:

1. Six, if 97% confidence for getting a color-matched pair of gloves randomly in the dark - on your first try - is good enough for you. Otherwise, thirteen.

2. Don't. Since they came from one side of the river, they have no need to cross the river (unless they do - in which case something exists on the other side, in which case someone build a bridge; they should try to find this bridge, and use it.)

3. Because hair curlers are not very photosensitive, and you'd have a very hard time getting the image off of them. Unless you're a professor, in which case your grad student will happily do it for you overnight instead of sleeping.

4. $$\frac{1}{0}$$ (seems a good candidate... unless you see something larger?)

5. Mauna Kea, Hawaii. Unless by "tallest" you subscribe to the popular notion of not measuring the height of the mountain, but merely how far it is from the center-of-mass of the earth; in which case, it's one of the Andes (I don't know which). Unless you'd rather save your effort and just measure how far the peak is displaced from the gravitational "sea level", in which case it would have been Mt. Everest, if you're not talking too many hundreds of thousands of years before the present era.

6. Six; the five whole cigars he's found, and one more he made from the five new butts.

7. I dunno - Sassafras? Eucalyptus?

8. The average man celebrates some seventy-seven birthdays; the average woman celebrates seventy-nine. But most are only born once, and have precisely one day of birth - unless they were born very close to midnight, of course.

9. It depends on what form you use, and in what language you speak, when you address your mom.

10. A pound of feathers is a lot - you should expect a few to be blown away by air currents and escape whatever container you're weighing them in - so the gold would wiegh more. Unless you're a pro experimentalist - with your nifty nine-figure digital precision scale, and you've taken all the precautions to prevent feather escape - in which case, the gold would weigh more, by the fraction a milligram. The feathers of course would be much more voluminous, and hence buoyant in atmospheric fluids. Unless you've got a rather large ultrahigh-vacuum chamber, and you can set up your precision-digital scale to measure the weight of what's inside it - in which case they would appear to weigh exactly the same. To within your margin of error. But then, shouldn't the much taller stack of feathers experience some picoscopic tidal forces, on the order of 10^-18 to one? You pull out a paper pad and your Pickett and come out with some tiny-looking number with three significant (but nonzero) digits. Your digital scale isn't anywhere near precise enough to measure the tidal forces acting on a pound of feathers. What to do? (If you do think of a workable method to measure forces this small, send an short email to the nice folks over at LIGO (link) - they'd be very interested).

11. edit - I misread this one - they will both be closer to Paris than to NYC, by the same amount.

12. 9 minutes, to within a 95% confidence interval of -5minutes +half-an-hour. Unless he's in a terrible hurry while operating power equiment - in which case something might go wrong and cause him to postpone his project.

13. 1,898 silver-dollars are worth more than 1,897 dollars by a difference of the value of one silver sollar.

14. Queue, arrrr! or sssss... and possibly some alternative spelling of "Hugh"

15. Johnny was a third child? That explains everything.

16. Depends on the size of the socks. Since it's dark and no one can see them, if their decoherence time is much longer than the length of time it takes you to take one out... then the question would need to be rephrased somewhat. Otherwise, four; because socks don't have any chiral properties I know about.

17. I was a bit worried about the use of "without... be widowed" when the participial form clearly was needed, but assuming this wasn't a trick... then she could in principle carry on three legal identities, one each in NYC, New Jersey, and eastern Pennsylvania. At least a few people have tried doing this.

18. Numbers for a sign. "1" costs $.12, "44" costs$.24, and the lady, wanting to buy both, apparently lives at a street number like "14498" or "5441" or similar.

19. Well, you're holding two. Did you pay for them? Do you have any at home in the fridge, that haven't spoiled yet?

20. The lamp. Then you can see what you're doing as you're preparing tinder for the wood-burning stove. The kerosene stove I wouldn't use, those things are dangerous.

Last edited by a moderator: Jan 29, 2006
12. Jan 29, 2006

### siddharth

13. Jan 29, 2006

### matthyaouw

Hooray, I got most of them right.
I don't agree with their answer for one though:
They say 13. I say 8. You can tell whether they be left or right handed gloves by feel alone, so you take one left glove, and then need 7 right gloves to ensure a match.

14. Jan 29, 2006

### mattmns

Hmm, I messed up a few, but I got some right too

15. Jan 29, 2006

### Staff: Mentor

Siddarth, I stated that I was going to post the link to the answers AFTER enough people had a chance to play. Please do not post answers to a thread that is not yours unless you have received permission.

16. Jan 29, 2006

### siddharth

Sorry, I apologise.
What I thought was that, since the answers were anyway hidden (in the sense that the link was to be clicked) it would not spoil the game in any way.

17. Jan 29, 2006

### Staff: Mentor

You KNOW people will look at the answers, it's too much tempatation.

18. Jan 29, 2006

### Gokul43201

Staff Emeritus
Looks to me like the only answer that hasn't been cracked is sequoia...assuming that's correct.

19. Jan 29, 2006

### Staff: Mentor

Yes, that would work. You should contact them.

20. Jan 29, 2006

### Staff: Mentor

That's correct!

Ok, all are done. Gee, you guys are good.