Math Is Fun Forum
  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#2 Re: Puzzles and Games » Battleship on the number line » 2006-09-09 15:35:23

tt

If it has the Earth involved, suppose the Earth is absolutely round and the number line is a straight line, you can ignite the bomb at the point of contact when t=0 before the battleship sailing off into space.

#3 Re: Puzzles and Games » Battleship on the number line » 2006-09-09 13:14:00

tt

Well, it looks more like a circle around the Earth on which the battleship is moving away from its starting point.

#4 Re: Puzzles and Games » Battleship on the number line » 2006-09-09 05:36:47

tt

I think it's impossible too unless two ends of the line joins each other straightly .

#5 Re: Ganesh's Puzzles » Brain Teasers » 2006-09-04 10:02:01

tt
ganesh wrote:


32. A, B, C, D, E, and F are sitting on six chairs placed around a round table, not necessarily in that order. A is between D and F. C is opposite D and D and E are not sitting next to each other. Which of these pairs are sitting next to each other?
(i) A and B (ii) C and E (iii) B and F (iv) A and C

My answer

#6 Re: Puzzles and Games » Coin Problem » 2006-09-04 08:55:20

tt

4d - 2o = 10a + b
4d - 3o = 10b + a ( a and b are arbitrary numbers between 1 and 9 inclusive)
Quite a lot of this cancels out, leaving o = 9(a-b).

(If o=9 then a-b=1, a>b; o<=d/2)
I came up with almost the same equations but yours are neater (using d instead of r) so I quote yours, hope you don't mind Mathsyperson.

I tried to cancel o out, leaving 4d=28a-17b
4d is even so 17b must be even or b even.
d, a, b are integers and d>0, a>0, b>0, a<>b
Replace a, b with value 1..9 or 2..8 and I have d=18; 8; 32; 46 mm
d=8 too small, d=46 too big a coin, that left d=18 mm (a=5, b=4) or 32 mm (a=7, b=4).
But it looks like only d=18 mm works.

What's wrong with my solution ?

#7 Re: Puzzles and Games » Coin Problem » 2006-09-04 06:52:19

tt

Did you compare two coin orders (from left to right) of 1-2-2-1 with 1-2-1-2 or 1-2-2-1 with 2-1-1-2 , Mathsyperson ?

#8 Re: Puzzles and Games » Noggin Twisters Website » 2006-09-04 05:15:56

tt

It looks like the explanation for the Kant's clock puzzle (in Serious puzzler) is not right. A good website, by the way, it has quite some tough puzzles.

#10 Re: Ganesh's Puzzles » Brain Teasers » 2006-09-03 22:01:50

tt
John E. Franklin wrote:

28)  I get 44 times at right angles.  I was too lazy, I only counted 22 from 6am to 6pm.
What is the answer for a seven-hour clock and a fourteen hour day??  Do you know Ganesh?  I don't.
The reason I ask is because with a 12 hour clock the 9 and the 3 are at right angles to the 12 at the top, so
the answer is less than 12 x 2 for 12 hours, but a seven hour clock would be weird, or a 5 hour clock too.
Hmmm....  I'll have to ponder this more later...

And I only see 42 times accounted for! I must have lost count around the dial.

#11 Re: Puzzles and Games » Coin Problem » 2006-08-09 14:47:11

tt

I meant the radius of the coin is 9 or 16 mm ?

#12 Re: Puzzles and Games » Coin Problem » 2006-08-02 17:46:41

tt

The diameter of the coins is 9 or 16 mm ?

#13 Re: Puzzles and Games » Devanté's Riddle House » 2006-08-02 11:37:17

tt

#43. What goes up and down the stairs without moving?


#47. What goes around the world but stays in a corner?

#49. Give me food, and I will live; give me water, and I will die. What am I?

#54. No sooner spoken than broken. What is it?

#55. A certain crime is punishable if attempted but not punishable if committed. What is it?

#59. I went into the woods and got it. I sat down to seek it. I brought it home with me because I couldn't find it. What is it?

#15 Re: Puzzles and Games » Devanté's Riddle House » 2006-08-02 10:38:39

tt

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?

#16 Re: Puzzles and Games » Five Pirates » 2006-08-02 07:07:51

tt

98, 0, 1, 0, 1
Well, too late to correct my silly mistake! Devante got it right.

#18 Re: Puzzles and Games » Who owns the fish? » 2005-08-08 13:29:50

tt

Let 1,2,3 be the 1st, 2nd, 3rd soldier.
Case 1:  R R B (1 and 2 wearing red cap and 3 wearing blue cap)
3 would have found out that he was wearing blue cap. But he couldn’t tell so this is not correct order .
Case 2:  R ? ?
2 would have known that he was wearing blue cap because if he was wearing red cap (case 1) then 3 figured out answer already.
But 2 couldn’t answer so 1 must be not wearing red cap.
Case 3: B ? ?
2,3 wouldn’t have enough facts to figure out the color of their caps.

1 considers case 1 and case 2 then he figures his cap is blue.

#20 Re: This is Cool » Solve this! » 2005-07-15 16:36:04

tt

Superman got 7 pound and Batman got 1 pound.

#21 Puzzles and Games » rabbit farm » 2005-07-14 17:42:13

tt
Replies: 13

I found this puzzle on web, no solutions :
Supposed that every 2 mature rabbits reproduce 2 baby rabbits each month and baby rabbits will be mature and reproduce after 2 months.
How many rabbits will you have after 10 months if you start with 2 mature rabbits ?

#22 Re: Ganesh's Puzzles » Problems and Solutions » 2005-07-14 17:04:47

tt

In 1992, the population was 120,000.

#23 Re: Puzzles and Games » Work done in time! » 2005-07-14 16:59:39

tt

The contractor needed 140 men X 60 days = 8400 man-days to do half the work. So he'll need 8400 more man-days to do the rest. He only has 40 days left, then he'll need   8400 man-days / 40 days = 210 men. He already has 140 men, so he has to hire 70 more men.

#24 Re: Puzzles and Games » Two cyclists » 2005-07-14 16:44:39

tt

They will cross each other at 7:42AM.

#25 Re: Puzzles and Games » The lorry and the tunnel » 2005-07-14 15:40:38

tt

He released some air in the tires so the lorry get lower a little but enough to go through the tunnel.

Board footer

Powered by FluxBB