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## #1 2008-12-05 22:10:14

ganesh
Moderator
Registered: 2005-06-28
Posts: 22,064

### Challenge of the Day:

Dec 6, 2008--->

#1. If

, then what is
equal to?

(1) 2(1+2m)    (2)

(3)
(4) 1 + m

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #2 2008-12-05 23:51:10

TooT
Member
Registered: 2008-09-20
Posts: 4

### Re: Challenge of the Day:

Last edited by TooT (2008-12-06 00:00:14)

TooT.

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## #3 2008-12-06 18:02:12

ganesh
Moderator
Registered: 2005-06-28
Posts: 22,064

### Re: Challenge of the Day:

Perfectly right, Toot! Keep it up!

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #4 2008-12-06 20:02:24

ganesh
Moderator
Registered: 2005-06-28
Posts: 22,064

### Re: Challenge of the Day:

Dec 7, 2008 --->

#2. A boy multiplies 987 by a certain number and obtains 559981 as the result. If in the answers, both 9s are wrong and the other digits are correct, what is the correct value of the product?
(1) 553681  (2) 555181  (3) 555681  (4) 556581

PS:- Marginally less difficult, being a Sunday

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #5 2008-12-07 02:14:23

ganesh
Moderator
Registered: 2005-06-28
Posts: 22,064

### Re: Challenge of the Day:

Dec 7, 2008 --->

#2A. The sum of all possible two-digit numbers  formed from three different one-digit natural numbers when divided by the sum of the original three numbers is equal to:
(1)   18    (2) 22    (3)  36    (4) None of these

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #6 2008-12-10 01:04:11

ganesh
Moderator
Registered: 2005-06-28
Posts: 22,064

### Re: Challenge of the Day:

Dec 10, 2008 --->

#3. If S be the sum, P the product and R the sum of reciprocals of n terms of a Geometric Progression,  prove that

.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #7 2008-12-10 15:54:02

Identity
Member
Registered: 2007-04-18
Posts: 934

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## #8 2008-12-11 00:46:36

ganesh
Moderator
Registered: 2005-06-28
Posts: 22,064

### Re: Challenge of the Day:

Very well done, Identity!!!

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #9 2008-12-11 02:00:19

ganesh
Moderator
Registered: 2005-06-28
Posts: 22,064

### Re: Challenge of the Day:

Dec 11, 2008 --->

#4. Find the sum of all the numbers that can be formed with the digits 1,2,3,4,5 taken 4 at a time.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #10 2008-12-16 01:11:30

ganesh
Moderator
Registered: 2005-06-28
Posts: 22,064

### Re: Challenge of the Day:

Dec 16, 2008 --->

#5. If

,
then find the value of
.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #11 2008-12-27 20:38:29

ganesh
Moderator
Registered: 2005-06-28
Posts: 22,064

### Re: Challenge of the Day:

Dec 28, 2008 --->

#6. The probability that a student is not a swimmer is

. Out of five students, find the probability that atleast 4 are swimmers.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #12 2008-12-28 00:28:55

ganesh
Moderator
Registered: 2005-06-28
Posts: 22,064

### Re: Challenge of the Day:

Dec 28, 2008 --->

#7. The cost of fuel in running an engine is proportional to the square of the speed and is #48 per hour for a speed of 16 kilometers per hour. Other expenses amount to \$300 per hour. What is the most economical speed?

#8. Evaluate:

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #13 2009-02-10 09:25:54

Clint945
Member
Registered: 2009-02-09
Posts: 3

### Re: Challenge of the Day:

#8 this is probably totally wrong but:

(x^2/a)e^ax - (2x/a^2)e^ax + (2/a^3)e^ax + C

sorry for the rubbish way of typing it... wish i knew how to put in the proper formula font :S

Last edited by Clint945 (2009-02-10 10:09:08)

Why did the maths tree fall over?
It had no real roots!

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## #14 2009-02-10 09:34:05

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

### Re: Challenge of the Day:

I get the same answer as you, but with the third term added instead of subtracted.

The formula font is called LaTeX, and if you're interested there's a tutorial stickied at the top of the Help Me board.

Why did the vector cross the road?
It wanted to be normal.

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## #15 2009-02-10 09:45:55

Clint945
Member
Registered: 2009-02-09
Posts: 3

### Re: Challenge of the Day:

oh yeah, it should be added,  because its (x^2/a)e^ax - ((2x/a^2)e^ax - ∫ (2/a)e^ax) so its + the third term. sorry my bad, fixed it i always forget those little minus signs... *sigh*

Last edited by Clint945 (2009-02-10 09:57:08)

Why did the maths tree fall over?
It had no real roots!

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## #16 2009-04-18 03:23:11

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 107,768

### Re: Challenge of the Day:

Hi ganesh;

My answer for #6

This is a bernoulli trial so:

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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## #17 2009-04-18 17:22:12

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 107,768

### Re: Challenge of the Day:

Hi ganesh;

The answer to #4 is (3) 555681

Last edited by bobbym (2009-04-28 07:14:40)

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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## #18 2009-04-19 01:58:07

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

### Re: Challenge of the Day:

Dec 11:

24*15*1111 = 399960

Why did the vector cross the road?
It wanted to be normal.

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## #19 2009-04-19 07:45:08

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 107,768

### Re: Challenge of the Day:

Hi ganesh;

Here is my answer to #10

Now multiply numerator and denominator by

Last edited by bobbym (2009-04-28 07:15:22)

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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## #20 2009-04-20 15:20:15

belowaverage
Member
Registered: 2009-04-20
Posts: 2

### Re: Challenge of the Day:

hai ganesh,

my ans to ur question #10 is

or 2.828427125

Last edited by belowaverage (2009-04-20 15:41:39)

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