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What is the correct pronunciation of George Pólya's last name? (I consider the way he pronounced his name to be the correct pronunciation.) —Preceding unsigned comment added by 98.114.146.57 ( talk) 04:20, 16 September 2009 (UTC)
We have a lock box on our house similar to this: http://www.buyasafe.net/S6-Supra-Pushbutton-Lockbox-Surface-Mount./M/B000M7OXPY.htm?traffic_src=froogle
My question is, how many possible combinations are there?
Here are a few things to consider: 1) There are 10 possible digits (numbers 0 through 9). 2) The order the numbers are pressed doesn't matter. 3) We chose a 4-digit combination; however, we could have selected anywhere from a 0 - 10 digit combination.
To break the 4 digit combination, the odds would be 10 x 9 x 8 x 7 = 5,040, right? However, when you consider we could have selected any number of digits, how does this affect the total number of possible combinations?
Thanks in advance for your help! —Preceding unsigned comment added by 209.206.158.57 ( talk) 17:02, 16 September 2009 (UTC)
Now, if you add up the number of 0-number combinations (1) + the number of 1-number combinations (10) + the number of 2-number combinations (45) + . . . + the number of 10-number combinations (1), you'll get 2^10 = 1,024.
One way to see why it's 2^10 is that each possible code either uses or doesn't use each of the 10 numbers. Thus, you either use '1' in your code, or you don't - 2 options. You either use '2' or you don't - 2 options. . . You either use '10' or you don't - 2 options. Multiply all those 2's together, boom.
Does that answer your question? - GTBacchus( talk) 17:19, 16 September 2009 (UTC)
Hi. I have a small problem with some homework but it's only in understanding what the question means.
"Let where z is a complex number. Writing for and for the inverse function, what is the image of the real line under the successive maps , , ? What is the image of this set of images under these maps?"
Letting z=x+iy, does the first part just mean determine , , ? And I don't have a clue for the second part. Any ideas? Thanks. 92.2.21.125 ( talk) 19:56, 16 September 2009 (UTC)
The second part of the question seems to be saying, do the same thing, but instead of just the real line as your starting set, use the set . Does that help at all? - GTBacchus( talk) 20:29, 16 September 2009 (UTC)
So, I have emailed my TA a question once and his response indicated he did not understand my question at all. I just got back from asking him other questions in person and he again did not understand what I was even asking, though I explained it several times. The professor does not have any office hours. So, I come here.
I'm doing a simple problem and I need help in understanding. The problem says to show if you have random variables X and Y then
They even give a hint to show that X + Y = max(X, Y) + min(X, Y). Well, this is a problem that is intuitively simple but I don't know how to explain it. I know if I am dealing with 2 real numbers x and y, then x + y = max(x, y) + min(x, y) and the proof is easy. So, it seems obvious to me from this that the same equation with random variables must be true. But, just saying it is obvious does not prove it. This is my only difficulty with this problem. Clearly, if I prove the equation with random variables, I can just take the Expectaion of both sides and use linearity and then subtract the min from both sides.
One thought is to let A = X + Y and B = max + min, new random variables. Then, P(A = a) = P(X + Y = a) = P(X = a - Y)... I don't know. We have only talked about functions of one random variable, but not functions of multiple random variables. StatisticsMan ( talk) 20:48, 16 September 2009 (UTC)
Mathematics desk | ||
---|---|---|
< September 15 | << Aug | September | Oct >> | September 17 > |
Welcome to the Wikipedia Mathematics Reference Desk Archives |
---|
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
What is the correct pronunciation of George Pólya's last name? (I consider the way he pronounced his name to be the correct pronunciation.) —Preceding unsigned comment added by 98.114.146.57 ( talk) 04:20, 16 September 2009 (UTC)
We have a lock box on our house similar to this: http://www.buyasafe.net/S6-Supra-Pushbutton-Lockbox-Surface-Mount./M/B000M7OXPY.htm?traffic_src=froogle
My question is, how many possible combinations are there?
Here are a few things to consider: 1) There are 10 possible digits (numbers 0 through 9). 2) The order the numbers are pressed doesn't matter. 3) We chose a 4-digit combination; however, we could have selected anywhere from a 0 - 10 digit combination.
To break the 4 digit combination, the odds would be 10 x 9 x 8 x 7 = 5,040, right? However, when you consider we could have selected any number of digits, how does this affect the total number of possible combinations?
Thanks in advance for your help! —Preceding unsigned comment added by 209.206.158.57 ( talk) 17:02, 16 September 2009 (UTC)
Now, if you add up the number of 0-number combinations (1) + the number of 1-number combinations (10) + the number of 2-number combinations (45) + . . . + the number of 10-number combinations (1), you'll get 2^10 = 1,024.
One way to see why it's 2^10 is that each possible code either uses or doesn't use each of the 10 numbers. Thus, you either use '1' in your code, or you don't - 2 options. You either use '2' or you don't - 2 options. . . You either use '10' or you don't - 2 options. Multiply all those 2's together, boom.
Does that answer your question? - GTBacchus( talk) 17:19, 16 September 2009 (UTC)
Hi. I have a small problem with some homework but it's only in understanding what the question means.
"Let where z is a complex number. Writing for and for the inverse function, what is the image of the real line under the successive maps , , ? What is the image of this set of images under these maps?"
Letting z=x+iy, does the first part just mean determine , , ? And I don't have a clue for the second part. Any ideas? Thanks. 92.2.21.125 ( talk) 19:56, 16 September 2009 (UTC)
The second part of the question seems to be saying, do the same thing, but instead of just the real line as your starting set, use the set . Does that help at all? - GTBacchus( talk) 20:29, 16 September 2009 (UTC)
So, I have emailed my TA a question once and his response indicated he did not understand my question at all. I just got back from asking him other questions in person and he again did not understand what I was even asking, though I explained it several times. The professor does not have any office hours. So, I come here.
I'm doing a simple problem and I need help in understanding. The problem says to show if you have random variables X and Y then
They even give a hint to show that X + Y = max(X, Y) + min(X, Y). Well, this is a problem that is intuitively simple but I don't know how to explain it. I know if I am dealing with 2 real numbers x and y, then x + y = max(x, y) + min(x, y) and the proof is easy. So, it seems obvious to me from this that the same equation with random variables must be true. But, just saying it is obvious does not prove it. This is my only difficulty with this problem. Clearly, if I prove the equation with random variables, I can just take the Expectaion of both sides and use linearity and then subtract the min from both sides.
One thought is to let A = X + Y and B = max + min, new random variables. Then, P(A = a) = P(X + Y = a) = P(X = a - Y)... I don't know. We have only talked about functions of one random variable, but not functions of multiple random variables. StatisticsMan ( talk) 20:48, 16 September 2009 (UTC)