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#41976 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-07-18 16:52:38

A cistern can be filled by two pipes A and B separately in 45 minutes and 36 minutes respectively. A tap C at the bottom can empty the cistern in 30 minutes. If the tap C is opened 7 minutes after the two pipes A and B are opened, in how many minutes will the cistern be full?

#41977 Re: Puzzles and Games » Test » 2005-07-18 16:48:50

A person was born in 1975 and he died in 1995. He was 25 years of age when he died. How?

(This one's a lateral thinking puzzle big_smile)

#41978 Re: This is Cool » Pick any five... » 2005-07-18 16:30:46

1 20  19
2 19  17
3 18  15
4 17  13
5 16  11
6 15   9
7 14   7
8 13   5
9 12   3
10 11 1

That's 100!

Re-arranging,
1 17  16
2 20  18
3 13  10
4 19  15
5 16  11
6 18  12
7 15   8
8 14   6
9 11   2
10 12  2
100 yet again!

Should it be always (n/2)² for 0 to n??? smile
(Just like the side total of a magic square containing numbers 1 to n² is
(n³+n)/2 ??? smile )

#41979 Re: Jokes » Limericks » 2005-07-18 16:20:26

I once knew someone named justlooking,
Who had a knack for hookin'
Everytime he tried his skill

#41980 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-07-17 20:16:17

I um unable to reply. I shall wait for your post and comment on that later, MathsIsFun.

ganesh wrote:

#4 (Without paper, pencil; Time limit : 1 minute)
The sum of three numbers is 174. The ratio of the second number to the third is 9:16 and the ratio of the first number to the third is 1:4. The second number is _______.

Since both the ratios have 4 or a multiple of 4 for C,
the ratio A:B:C = 4:9:16.
The sum of these is 29, and it can be noticed 174 is 29 x 6.
Therefore, the second number is 9 x 6, that is 54.

#41981 Re: Puzzles and Games » Gas Cylinders » 2005-07-17 17:27:14

Ist truck:-    3 full cylinders, 1 half-full and 3 empty
IInd truck:-  2 full cylinders, 3 half-full and 2 empty
IIIrd truck:- 2 full cylinders, 3 half-full and 2 empty

PS:- The Moderator may remove my reply if he/she wants it to be left open.

#41982 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-07-17 17:17:01

You are right, Mathsy! smile
#4 (Without paper, pencil; Time limit : 1 minute)
The sum of three numbers is 174. The ratio of the second number to the third is 9:16 and the ratio of the first number to the third is 1:4. The second number is _______.

#41983 Re: Help Me ! » Hi » 2005-07-16 17:43:13

Jenilia, we shall prepare you for the Olympiad;
I shall start with my first lesson,
do you know how recurring decimals are converted into fractions?
Lets assume x=0.1414141414....................
100 x = 14.14141414.....................
Deducting equation (2) from (1),
99x = 14
x = 14/99

#41984 Re: This is Cool » Solve this! » 2005-07-16 17:39:38

Mathsy, you are, I repeat, you are, really smart! smile

#41985 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-07-16 00:24:18

I saw this problem and I was impressed. I didn't know someone had posted a similiar problem earlier. Okay, I shall give the solution and post a new problem instead.
The solution :- 6 /(1-3/4)


The new problem #3
Imagine you are writing numbers from 1 to 1000 on a piece of paper. How many times would you write the number'9'? tongue

#41986 Re: This is Cool » Solve this! » 2005-07-16 00:13:57

tt is, relatively, a newcomer, and he /she solves my problems quickly. cool
I had requested this member to wait for the others to post their replies, maybe he/she thought this was unanswered for quite some time. cool

#41987 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-07-16 00:06:12

I shall try to solve that when I start the next week,
here's my problem for the day roll

Using the numbers 1, 3, 4, and 6, together with the operations +, -, ×, and ÷, and unlimited use of brackets, make the number 24.  Each number must be used precisely once.  Each operation may be used zero or more times.  Decimal points are not allowed, nor is implicit use of base 10 by concatenating digits, as in 64 - 31.

#41988 Re: Puzzles and Games » Test » 2005-07-15 23:08:39

I am unable to guess why she did it!

#41991 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-07-15 22:43:33

Thats right!
This is how it is solved.
40 litres of milk and water contain 10% water.
Therefore, the milk content is 36 litres and water is 4 litres.
Lets assume x litres of water are added to make water 20%.
The ratio of water to the total becomes
4+x/40+x
this is equal to 20/100 or 1/5.
4+x/40+x = 1/5,
5(4+x) = 40+x
20+5x = 40+x
4x=20
x=5 litres

#41992 Re: This is Cool » "A Maths Dictionary for Kids" » 2005-07-14 23:18:10

Don't hate Mathematics, Zoe! Mathematics is fun, believe me! wink

#41993 Re: Dark Discussions at Cafe Infinity » Wink Murder » 2005-07-14 23:15:58

Roraborealis wrote:

I wonder if ganesh would like to play?

I am too old...I am more than 10,000 days old! roll

#41995 Re: Jokes » Limericks » 2005-07-14 19:52:23

who looked much like a lizard

#41996 Re: Puzzles and Games » rabbit farm » 2005-07-14 19:41:49

You mean 144? My friend says it is ___!

#41997 Re: Maths Teaching Resources » Welcome » 2005-07-14 18:59:54

I can live on 100 litres of coke a month, without food big_smile

#41998 Re: Help Me ! » I need your help » 2005-07-14 17:57:42

ganesh wrote:

I discovered that 2^20 ends in 76.
Thereafter, any number of the form 2^20n ends in 76.
Similarly, any number of the form 2^100n ends in 376.
Next, I had to know the last few digits of 2^500 and 2^2500.
When I learnt that they are 9376 and 09376, I was excited.
Because, any number of the form 2^500n would then have to end in 9376
and every 2^2500n would have to end in 09376.

This is what Rora was talking about. You are too young to understand this, Maxine. This is about higher powers of the number 2.

#41999 Re: Puzzles and Games » rabbit farm » 2005-07-14 17:47:58

This is much more complicated than what I thought! smile

#42000 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-07-14 17:10:52

Outstanding! You are really supersmart! big_smile
Try this one....But don't post your reply immediately.
Let others too try. big_smile

(2) A mixture of 40 liters of milk and water contains 10% water. How much water must be added to make water 20% in the new mixture? smile

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