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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?
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 )
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???
(Just like the side total of a magic square containing numbers 1 to n² is
(n³+n)/2 ??? )
I once knew someone named justlooking,
Who had a knack for hookin'
Everytime he tried his skill
I um unable to reply. I shall wait for your post and comment on that later, MathsIsFun.
#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.
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.
You are right, Mathsy!
#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 _______.
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
Mathsy, you are, I repeat, you are, really smart!
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'?
tt is, relatively, a newcomer, and he /she solves my problems quickly.
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.
I shall try to solve that when I start the next week,
here's my problem for the day
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.
I am unable to guess why she did it!
I am jumping in!
You are correct, tt!
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
Don't hate Mathematics, Zoe! Mathematics is fun, believe me!
I wonder if ganesh would like to play?
I am too old...I am more than 10,000 days old!
That is close to a 1,000 gallons!
who looked much like a lizard
You mean 144? My friend says it is ___!
I can live on 100 litres of coke a month, without food
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.
This is much more complicated than what I thought!
Outstanding! You are really supersmart!
Try this one....But don't post your reply immediately.
Let others too try.
(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?