Author 
Topic 
MooKids Caldari The Graduates Morsus Mihi 
Posted  2009.11.07 17:56:00  [ 1]
Where N=950 South Korean woman passes driving exam on 950th attemptSeriously, what is wrong with some people? You would think after a while you would realize that maybe you should STUDY. If I remember, this woman refused to get a tutor, even though she has spent $4500 USD on administrative fees. I would think the law of averages would mean she would have had a better chance at guessing. Now of course she has to go for the actual road test. I wonder how many times/how many car wrecks she has to go through to actually get a license. 
Sazkyen 
Posted  2009.11.07 18:29:00  [ 2]
And now, in a magazine, a new ad appears:
"Looking for experienced driver for my vegetables business. Have acquired the license two days ago so it's okay now."
I mean if someone can fail the exam 950 times, then surely there has to be something wrong with that person.

Tamia Clant New Dawn Corp New Eden Research. 
Posted  2009.11.07 19:44:00  [ 3]
Originally by: MooKids I would think the law of averages would mean she would have had a better chance at guessing.
Assuming the test has 4 options per question, and if my maths are right, her chances were approximately 0.25%, or one success every 400 tries. ...I'll get my coat. 
goodby4u Valor Inc. Valor Empire 
Posted  2009.11.07 20:01:00  [ 4]
Originally by: Tamia Clant
Originally by: MooKids I would think the law of averages would mean she would have had a better chance at guessing.
Assuming the test has 4 options per question, and if my maths are right, her chances were approximately 0.25%, or one success every 400 tries.
...I'll get my coat.
I don't remember what one needs to score on the driving test to pass, but assuming there are 4 questions, the chances of her getting each question right is 1/4, or 25% However, the chances of her getting 100% of the questions correct on a test with 100 questions in this case would be .25%, though I have never been really good with the maths so I am probably wrong. 
Tamia Clant New Dawn Corp New Eden Research. 
Posted  2009.11.07 20:21:00  [ 5]
Edited by: Tamia Clant on 07/11/2009 20:21:26 Originally by: goodby4u
Originally by: Tamia Clant
Originally by: MooKids I would think the law of averages would mean she would have had a better chance at guessing.
Assuming the test has 4 options per question, and if my maths are right, her chances were approximately 0.25%, or one success every 400 tries.
...I'll get my coat.
I don't remember what one needs to score on the driving test to pass, but assuming there are 4 questions, the chances of her getting each question right is 1/4, or 25%
However, the chances of her getting 100% of the questions correct on a test with 100 questions in this case would be .25%, though I have never been really good with the maths so I am probably wrong.
Assuming a test has 2 questions with 4 options, your chances of getting both right are (1/4)*(1/4), not (1/4)*2, so you can't just calculate the probability of one question then multiply it by the number of questions. This is now a math thread. 
goodby4u Valor Inc. Valor Empire 
Posted  2009.11.07 20:34:00  [ 6]
Edited by: goodby4u on 07/11/2009 20:35:24 If this were the case, she would have only a 1/4194304 chance of getting just 10 questions right by guessing.
Assuming 1/4*1/4*1/4*1/4*1/4*1/4*1/4*1/4*1/4*1/4. 
Merin Ryskin Peregrine Industries

Posted  2009.11.07 23:19:00  [ 7]
ST371 to the rescue!
The chance of doing it by blind luck depends on the total number of questions (more questions = blind guessing is more likely to give you close to the average of 25%), and it is NOT just the chance of getting 60 questions correct. Remember, you just need ANY 60 points, not a specific 60 where you would just take 0.25^x, where x is the number of correct answers you need.
The chance of getting k successes out of n trials with chance of success p is (IOW, a binomial distribution) is given by {(p)^k}*{(1p)^(nk)}*(n k), where (n k) is n!/(n!*(nk)!), "the number of ways to choose n out of k", since the order of the questions you get right doesn't matter. The probability of getting 60 or more correct is the sum of the probabilities: {p(60 right) + p(61 right) ... + p(100 right)}.
Since I'm not going to calculate all these by hand, looking it up off the binomial table gives a probability of 0.00032 of getting a 60/100 on the test for a 100 question test. IOW, she would have to take the test 3125 times to pass it by blind chance alone. So while her studying may have been severely lacking, it's still better than blind luck.
On the other hand, if the test is only 10 questions long, the chance of getting a 6/10 is .00351, or 285 attempts to get the 6/10 by just guessing. In that case, she did considerably worse than blind luck.
Of course all of this assumes a 4answer multiple choice test, which may or (more likely) may not be correct. 
ceaon 
Posted  2009.11.08 02:17:00  [ 8]
Originally by: Merin Ryskin ST371 to the rescue!
The chance of doing it by blind luck depends on the total number of questions (more questions = blind guessing is more likely to give you close to the average of 25%), and it is NOT just the chance of getting 60 questions correct. Remember, you just need ANY 60 points, not a specific 60 where you would just take 0.25^x, where x is the number of correct answers you need.
The chance of getting k successes out of n trials with chance of success p is (IOW, a binomial distribution) is given by {(p)^k}*{(1p)^(nk)}*(n k), where (n k) is n!/(n!*(nk)!), "the number of ways to choose n out of k", since the order of the questions you get right doesn't matter. The probability of getting 60 or more correct is the sum of the probabilities: {p(60 right) + p(61 right) ... + p(100 right)}.
Since I'm not going to calculate all these by hand, looking it up off the binomial table gives a probability of 0.00032 of getting a 60/100 on the test for a 100 question test. IOW, she would have to take the test 3125 times to pass it by blind chance alone. So while her studying may have been severely lacking, it's still better than blind luck.
On the other hand, if the test is only 10 questions long, the chance of getting a 6/10 is .00351, or 285 attempts to get the 6/10 by just guessing. In that case, she did considerably worse than blind luck.
Of course all of this assumes a 4answer multiple choice test, which may or (more likely) may not be correct.
ahhh my brain aaaahh overload 
Xai Dun 
Posted  2009.11.08 02:30:00  [ 9]
Edited by: Xai Dun on 08/11/2009 02:30:26

Merin Ryskin Peregrine Industries

Posted  2009.11.08 02:37:00  [ 10]
Originally by: ceaon
Originally by: Merin Ryskin ST371 to the rescue!
The chance of doing it by blind luck depends on the total number of questions (more questions = blind guessing is more likely to give you close to the average of 25%), and it is NOT just the chance of getting 60 questions correct. Remember, you just need ANY 60 points, not a specific 60 where you would just take 0.25^x, where x is the number of correct answers you need.
The chance of getting k successes out of n trials with chance of success p is (IOW, a binomial distribution) is given by {(p)^k}*{(1p)^(nk)}*(n k), where (n k) is n!/(n!*(nk)!), "the number of ways to choose n out of k", since the order of the questions you get right doesn't matter. The probability of getting 60 or more correct is the sum of the probabilities: {p(60 right) + p(61 right) ... + p(100 right)}.
Since I'm not going to calculate all these by hand, looking it up off the binomial table gives a probability of 0.00032 of getting a 60/100 on the test for a 100 question test. IOW, she would have to take the test 3125 times to pass it by blind chance alone. So while her studying may have been severely lacking, it's still better than blind luck.
On the other hand, if the test is only 10 questions long, the chance of getting a 6/10 is .00351, or 285 attempts to get the 6/10 by just guessing. In that case, she did considerably worse than blind luck.
Of course all of this assumes a 4answer multiple choice test, which may or (more likely) may not be correct.
ahhh my brain aaaahh overload
TL,DR: 1) The odds of getting it right by blind chance depend on unknown information about the test. The woman is a ****ing idiot who should not under any circumstances be allowed to drive, but she may or may not have done better than just random guessing. 2) Every attempted explanation before mine is wrong, and the actual math is much more complicated. 
Lance Fighter Amarr 
Posted  2009.11.08 02:40:00  [ 11]
Originally by: Merin Ryskin
Originally by: ceaon
Originally by: Merin Ryskin ST371 to the rescue!
The chance of doing it by blind luck depends on the total number of questions (more questions = blind guessing is more likely to give you close to the average of 25%), and it is NOT just the chance of getting 60 questions correct. Remember, you just need ANY 60 points, not a specific 60 where you would just take 0.25^x, where x is the number of correct answers you need.
The chance of getting k successes out of n trials with chance of success p is (IOW, a binomial distribution) is given by {(p)^k}*{(1p)^(nk)}*(n k), where (n k) is n!/(n!*(nk)!), "the number of ways to choose n out of k", since the order of the questions you get right doesn't matter. The probability of getting 60 or more correct is the sum of the probabilities: {p(60 right) + p(61 right) ... + p(100 right)}.
Since I'm not going to calculate all these by hand, looking it up off the binomial table gives a probability of 0.00032 of getting a 60/100 on the test for a 100 question test. IOW, she would have to take the test 3125 times to pass it by blind chance alone. So while her studying may have been severely lacking, it's still better than blind luck.
On the other hand, if the test is only 10 questions long, the chance of getting a 6/10 is .00351, or 285 attempts to get the 6/10 by just guessing. In that case, she did considerably worse than blind luck.
Of course all of this assumes a 4answer multiple choice test, which may or (more likely) may not be correct.
ahhh my brain aaaahh overload
TL,DR:
1) The odds of getting it right by blind chance depend on unknown information about the test. The woman is a ****ing idiot who should not under any circumstances be allowed to drive, but she may or may not have done better than just random guessing.
2) Every attempted explanation before mine is wrong, and the actual math is much more complicated.
3) who the **** actually cares about the math? Or the subject? 
Blane Xero Amarr The Firestorm Cartel

Posted  2009.11.08 12:17:00  [ 12]
Originally by: Lance Fighter
Originally by: Merin Ryskin
Originally by: ceaon
Originally by: Merin Ryskin ST371 to the rescue!
The chance of doing it by blind luck depends on the total number of questions (more questions = blind guessing is more likely to give you close to the average of 25%), and it is NOT just the chance of getting 60 questions correct. Remember, you just need ANY 60 points, not a specific 60 where you would just take 0.25^x, where x is the number of correct answers you need.
The chance of getting k successes out of n trials with chance of success p is (IOW, a binomial distribution) is given by {(p)^k}*{(1p)^(nk)}*(n k), where (n k) is n!/(n!*(nk)!), "the number of ways to choose n out of k", since the order of the questions you get right doesn't matter. The probability of getting 60 or more correct is the sum of the probabilities: {p(60 right) + p(61 right) ... + p(100 right)}.
Since I'm not going to calculate all these by hand, looking it up off the binomial table gives a probability of 0.00032 of getting a 60/100 on the test for a 100 question test. IOW, she would have to take the test 3125 times to pass it by blind chance alone. So while her studying may have been severely lacking, it's still better than blind luck.
On the other hand, if the test is only 10 questions long, the chance of getting a 6/10 is .00351, or 285 attempts to get the 6/10 by just guessing. In that case, she did considerably worse than blind luck.
Of course all of this assumes a 4answer multiple choice test, which may or (more likely) may not be correct.
ahhh my brain aaaahh overload
TL,DR:
1) The odds of getting it right by blind chance depend on unknown information about the test. The woman is a ****ing idiot who should not under any circumstances be allowed to drive, but she may or may not have done better than just random guessing.
2) Every attempted explanation before mine is wrong, and the actual math is much more complicated.
3) who the **** actually cares about the math? Or the subject?
Mathematicians. Everywhere. Suddenly. 
Spaztick Terminal Impact Kairakau 
Posted  2009.11.08 14:43:00  [ 13]
How did the constipated mathematician solve his problem?
He worked it out with a pencil. 
Jacob Mei Gallente 
Posted  2009.11.08 16:27:00  [ 14]
The math aside does anyone find it odd that it never got to the point that someone went "look, you've taken this test hundreds of times and its just the exam. Odds are you'r going to be a danger on the road so your blocked." I mean surely after the 50th time some flag went up, let alone the 900th time. 
Emil Erlenmeyer 
Posted  2009.11.08 17:20:00  [ 15]
Originally by: Jacob Mei The math aside does anyone find it odd that it never got to the point that someone went "look, you've taken this test hundreds of times and its just the exam. Odds are you'r going to be a danger on the road so your blocked." I mean surely after the 50th time some flag went up, let alone the 900th time.
I know some of those tests aren't very well put together but isn't their main purpose generally to rule out all the idiots, especially like this ******ed lady? 
Kazang Wrecking Shots 
Posted  2009.11.08 20:57:00  [ 16]
Pretty sure there is a limit to the number of times you can the do the test in the UK, not sure what it is but it's a hell of a lot less than 950. 
Gloria Culero 
Posted  2009.11.09 08:20:00  [ 17]
Originally by: Kazang Pretty sure there is a limit to the number of times you can the do the test in the UK, not sure what it is but it's a hell of a lot less than 950.
I'm here in oregon, usa and we don't have a total limit on how many test you can take, but we do have a limit on how often you can take it after you fail. I remember hearing about this woman after she failed #700(or a different woman in south korea) Did the math and forgot the exact answer but it was in the decades she would have tried and failed in oregon to get that high. I'm my opinion, and I'm being very liberal here, ten should be the limit. Period!! More like three but I give 'em ten. 
