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#476 Re: Help Me ! » discrete or continuous Uni.Ran.Var.? » 2007-07-26 20:13:07

Rectangle of X and Y distribution:
(1,1) (3,1) (3,4) (1,4)

(X,Y) is equally distributed in this rectangle with f(x,y)=1/6=1/2*1/3, on the assumption that X and Y are independent.

draw a line y=x, any (x,y) above this obeys y>x, whereas any (x,y) below this obeys y<x
y=x cut the rectangle at (1,1) and (3,3)
The area of the rectangular above the line is 4
Hence the probability that Y>X is
1/6*4=2/3

#477 Re: Help Me ! » Definite integral » 2007-07-25 12:54:54

Ricky's result in Post 9 is 2a² times as large as my result, because what he evaluates is 2a² times as large as the original question, too.

#479 Re: Help Me ! » Definite integral » 2007-07-24 14:15:47

Uhh, +/- mistake corrected. Now my result is not 0 but a²/3, consistent with your result in Post 19.

#480 Re: Help Me ! » Definite integral » 2007-07-24 02:48:00

My answer is 0. Can anyone evaluate it by software?

---my new answer is a²/3

#482 Re: Help Me ! » Definite integral » 2007-07-24 02:34:09

Ricky wrote:

George, your first step seems to be saying that:

Which does seem to be the case.

Uhh... you are right! I'm correcting it.

#484 Re: Dark Discussions at Cafe Infinity » LEGO Challenge » 2007-07-23 20:34:01

Hmm, I prefer using metal pieces with holes to Lego in building my designs.

#486 Re: Jokes » I used to think 1 add 1 was 2, but now... » 2007-07-23 20:24:21

The essence of counting is identity. Though the last scoop is one ball, but it cannot be considered equivalent to either of the original two scoops.

#487 Re: Help Me ! » ORDER Statistics (extremely difficult problem) » 2007-07-23 20:21:13

It's like tossing n dices, and to get the chance of getting the sum of dice values
less than a(sounding ei) times of the least dice value.

But it's so hard !!!!!!!!!

#488 Re: Help Me ! » Definite integral » 2007-07-23 20:06:02

when x=0, x/2=0; when x=π/2, x/2=π/4

Thus the result is

#489 Re: Help Me ! » Definite integral » 2007-07-23 19:52:02

Next, Define S(θ)

Then







So

#490 Re: Help Me ! » Definite integral » 2007-07-23 19:21:43

First, using trig formula cos(2x)=cos²(x)-sin²(x)

The original problem equals to


#491 Re: Dark Discussions at Cafe Infinity » Ten Politically Incorrect Truths About Human Nature » 2007-07-10 19:44:09

Awlsome!!

After going through so many evasive, imaginary pages of psychology, I come across some truth here!

Truth is truth- no matter how hard you try to ignore it, it will relentless show you are wrong, it is right.

#492 Re: Help Me ! » Proving a vector property » 2007-06-27 14:25:53

are u and v both 3 dimensional?

#494 Re: This is Cool » The Classic Slide Rule » 2007-06-21 14:00:14

BTW 1.5D1 can be generated by sliding the middle bar, using C
C   1   1.5
D   D[sub]1[/sub]  1.5D[sub]1[/sub]

#495 Re: This is Cool » The Classic Slide Rule » 2007-06-21 13:57:43

Hey, guys! Sorry for the delay of the last post on powers:

First, let me explain the basics:
Shifting Bases:

Suppose you have got a table of almost all of powers of 3,
..., 3^-0.1, 3^0, 3^0.1, 3^0.2,...
Now, however, you are to calculate a power of 9 instead of 3.

9^1.5

You cannot multiply
However, you know from the table of powers of 3 that 9=3^2
Then 9= (3[sup]2[/sup])[sup]1.5[/sup]=3[sup](2*1.5)[/sup]
Find 2*1.5 and by the table you can immediately get the answer, the power of 9

So with multiplication, a table of powers of a particular number can serve to find powers of any positive number.

That's how a slide rule works to help you guage a power.
LL scale, the power tables of e, e^0.1, e^0.01, e^-1, e^-0.1, e^-0.01 calculate more than powers of the only 5 e related bases.

Now suppose you are calculate 9^1.5 by the scale of e^x and multiplication on exponetial.

Simulated Slide Rule

Use the simulated slide rule (SSR) above
Flip the SSR, find LL3+ at the bottom, e to 20M (meaning 20,000,000)
LL3+=e^D
Now you should find D[sub]1[/sub]
which satisfy
e[sup]D1[/sup]=9

D          D[sub]1[/sub]
LL3+       9

and then find D[sub]2[/sub]=1.5D[sub]1[/sub] on D scale, by multiplication of slide rule.

then you can get e^D[sub]2[/sub]=9^1.5
D        D[sub]2[/sub]
LL3+    e^D[sub]2[/sub]

Next topic is shifting LL scales, solving too large and too small problems.

#496 Re: This is Cool » Microsoft Math 3.0?? » 2007-06-21 13:19:36

Who is gonna be the successor of Netscape or ICQ?
Who is gonna be the next victim of all-mighty Microsoft?
Wolfram, producer of Mathematica?
Or Maple?

PS: I use as little Microsoft as possible: Maxthon Explorer, Foxmail Mailreceiver, Skype communicator.

#497 Re: Help Me ! » infinite series » 2007-06-21 13:02:05

However this formula almost only makes it harder to solve.
I prefer the original one.:/

#498 This is Cool » Microsoft Math 3.0?? » 2007-06-20 19:46:32

George,Y
Replies: 27

Beating maple, mathematica all over???

5A8342AD61FE1C5F77925002E971F1A0.jpg

D5EE42CAFD3A93238CDD2B40FFCE1E0A.jpg

Microsoft Empire???faint

#499 Re: Dark Discussions at Cafe Infinity » How do you enjoy lemon? » 2007-06-11 22:33:21

Recently I came across an assertion that brush your teeth with lemon can make them whiter...

#500 Re: Help Me ! » ellipse » 2007-06-11 14:29:19

The total distance of red line segments together is S.

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