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

You are not logged in.

- Topics: Active | Unanswered

Pages: **1**

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 22,555

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.

Offline

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

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

TooT.

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 22,555

**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.

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 22,555

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.

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 22,555

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

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

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 22,555

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

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

Offline

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

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 22,555

**Very well done, Identity!!!**

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

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 22,555

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.

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

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 22,555

Dec 16, 2008 --->

#5. If

,then find the value of

.

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

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 22,555

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

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 22,555

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:

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

Offline

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

#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!

Offline

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

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.

Offline

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

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!

Offline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 108,432

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.**

**Online**

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 108,432

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.**

**Online**

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

Dec 11:

24*15*1111 = 399960

Why did the vector cross the road?

It wanted to be normal.

Offline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 108,432

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.**

**Online**

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

hai ganesh,

my ans to ur question #10 is

or 2.828427125*Last edited by belowaverage (2009-04-20 15:41:39)*

Offline

Pages: **1**