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#901 2011-06-08 05:58:33
- anonimnystefy
- Real Member
- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,049
Re: Oral puzzles
hi ganesh
Last edited by anonimnystefy (2011-06-08 05:58:46)
Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.
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#902 2011-06-08 06:02:48
- anonimnystefy
- Real Member
- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,049
Re: Oral puzzles
hi bobbym
i think that you missed the minus sign instead of plus.
Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.
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#903 2011-06-08 08:26:14
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Oral puzzles
Hi anonimnystefy;
I think you are right my answer was kaboobly doo. I fixed it and advised ganesh of the correction.
Hi ganesh;
Sorry for the confusion. Check anonimnystefy's answer and we can continue.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#904 2011-06-08 08:26:15
- reconsideryouranswer
- Member
- Registered: 2011-05-11
- Posts: 171
Re: Oral puzzles
Hi bobbym,
The solution 1048 is perfect. Good work!
#1049. Find the sum to n terms of the series
.
bobbym and anonimnystefy,
for #1049, neither of your answers *were* correct.
Notice if n = 1 in your formulas, neither produces 2/3, which is the 1st term of the series.
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bobbym,
Then, the summation on the right-hand side of the subtraction sign is equal to:
The whole infinite series (**) sums to 1/2.
Edit:
------
I will take the credit for the solution.
Last edited by reconsideryouranswer (2011-06-08 08:41:33)
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I wish a had a more interesting signature line.
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#905 2011-06-08 08:28:56
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Oral puzzles
Hi;
Yes, I know, it has already been straightened out. Check the earlier posts to yours. I edited my answer. It now generates the sum. Just a latex error.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#906 2011-06-08 09:11:37
- reconsideryouranswer
- Member
- Registered: 2011-05-11
- Posts: 171
Re: Oral puzzles
These questions are to be attempted to be answered orally,
and attempted within a minute, without the use of paper, pen/pencil and calculator.
After sampling many questions here, I would propose the above alteration to be realistic. And my
involvement/effort to my solution to #1049 would be representative of that change.
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Edit:
------
_______________________________________________________________________
ashwil
Full Member
Re: Oral puzzles
mathsy, 2 easy ways of getting approximate answers to 20 without a calculator:-
a) every power of 10 requires just over 3 powers of 2. Therefore 50 powers of 2
suggests between 15 and 16 powers of 10.
b) If you know that log 2 = 0.3010 (which you should!), then log 2^50 = 15.05.
Again, about 15 powers of 10
By both methods, this gives me 16 digits in the answer.
_______________________________________________________________________
But how would a person know that they would be correct with either of those methods?
Last edited by reconsideryouranswer (2011-06-08 09:16:44)
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#907 2011-06-08 17:22:09
- Jai Ganesh
- Administrator
- Registered: 2005-06-28
- Posts: 48,422
Re: Oral puzzles
Hi reconsideryouranswer, anonimnystefy, and bobbym,
The solution 1049 given by reconsideryouranswer is perfect. Excellent!
I carry on with the puzzles.
#1050. If
, find the value of x.It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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#908 2011-06-08 19:37:11
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Oral puzzles
Hi ganesh;
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#909 2011-06-08 23:10:12
- Jai Ganesh
- Administrator
- Registered: 2005-06-28
- Posts: 48,422
Re: Oral puzzles
Hi bobbym,
The solution given 1050 is perfect. Excellent performance!
#1051.
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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#910 2011-06-08 23:16:35
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Oral puzzles
Hi;
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#911 2011-06-09 18:01:25
- Jai Ganesh
- Administrator
- Registered: 2005-06-28
- Posts: 48,422
Re: Oral puzzles
Hi bobbym,
The solution 1051 is in order. Good work!
#1052. If
, then what is the value of a and b?It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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#912 2011-06-09 19:22:30
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Oral puzzles
Hi;
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#913 2011-06-10 05:00:08
- anonimnystefy
- Real Member
- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,049
Re: Oral puzzles
hi ganesh
Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.
Offline
#914 2011-06-10 16:18:49
- Jai Ganesh
- Administrator
- Registered: 2005-06-28
- Posts: 48,422
Re: Oral puzzles
Hi bobbym and anonimnystefy,
The solution 1052 is perfect. Excellent!
#1053.
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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#915 2011-06-10 16:22:03
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Oral puzzles
Hi ganesh;
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#916 2011-06-11 17:20:29
- Jai Ganesh
- Administrator
- Registered: 2005-06-28
- Posts: 48,422
Re: Oral puzzles
Hi bobbym,
The solution 1053 is perfect. Brilliant work!
#1054.
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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#917 2011-06-11 17:31:10
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Oral puzzles
Hi ganesh;
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#918 2011-06-12 01:39:37
- anonimnystefy
- Real Member
- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,049
Re: Oral puzzles
hi ganesh
Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.
Offline
#919 2011-06-12 02:03:44
- Jai Ganesh
- Administrator
- Registered: 2005-06-28
- Posts: 48,422
Re: Oral puzzles
Hi bobbym and anonimnystefy,
The solution 1054 is correct. Remarkable!
#1055.
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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#920 2011-06-12 02:13:04
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Oral puzzles
Hi;
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#921 2011-06-12 16:36:11
- Jai Ganesh
- Administrator
- Registered: 2005-06-28
- Posts: 48,422
Re: Oral puzzles
Hi bobbym,
The solution 1055 is correct. Neat job!
#1056.
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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#922 2011-06-12 18:37:03
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Oral puzzles
Hi;
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#923 2011-06-13 17:13:08
- Jai Ganesh
- Administrator
- Registered: 2005-06-28
- Posts: 48,422
Re: Oral puzzles
Hi bobbym,
The solution 1056 is correct. Neat job!
#1057.
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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#924 2011-06-13 20:04:56
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Oral puzzles
Hi ganesh;
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#925 2011-06-13 21:22:53
- Jai Ganesh
- Administrator
- Registered: 2005-06-28
- Posts: 48,422
Re: Oral puzzles
Hi bobbym,
The solution 1057 is perfect. Neat job!
#1058. If
, then what would be the value of ?It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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