Can someone help me understand this question :
n question are either true or false. What is the minimum value of n for which (p) of all true <1/1000?
thanx
Probability Query
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Hi,
Probability that each each question is correct is 1/2.
So, probability of gettign all 'n' questions correct is (1/2)^n
So, (1/2)^n < 1/1000 => 2^n > 1000
2^10 = 1024
So, n >= 10
Minimum value of n is 10.
Probability that each each question is correct is 1/2.
So, probability of gettign all 'n' questions correct is (1/2)^n
So, (1/2)^n < 1/1000 => 2^n > 1000
2^10 = 1024
So, n >= 10
Minimum value of n is 10.
Last edited by Frankenstein on Thu Jun 30, 2011 8:33 pm, edited 1 time in total.
Cheers!
Things are not what they appear to be... nor are they otherwise
Things are not what they appear to be... nor are they otherwise
Can you please explain this stmt - "So, (1/2)^n < 1000 => 2^n > 1000"Frankenstein wrote:Hi,
Probability that each each question is correct is 1/2.
So, probability of gettign all 'n' questions correct is (1/2)^n
So, (1/2)^n < 1000 => 2^n > 1000
2^10 = 1024
So, n >= 10
Minimum value of n is 10.
Thanks!
- Treker
- Treker
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Hi,treker wrote:Can you please explain this stmt - "So, (1/2)^n < 1000 => 2^n > 1000"Frankenstein wrote:Hi,
Probability that each each question is correct is 1/2.
So, probability of gettign all 'n' questions correct is (1/2)^n
So, (1/2)^n < 1000 => 2^n > 1000
2^10 = 1024
So, n >= 10
Minimum value of n is 10.
That was a typo. I have edited now. If you are interested in the underlying principle,
If a and b are positive and a > b, then 1/a < 1/b.
Example: 3>2 .. 1/3 < 1/2.
Cheers!
Things are not what they appear to be... nor are they otherwise
Things are not what they appear to be... nor are they otherwise
- amit2k9
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probability of having a right or wrong in question = 1/2
thus 1/2^n < 1/1000 is what being asked here.
hence 2^n = 1024 is sufficient meaning n = 10.
thus 1/2^n < 1/1000 is what being asked here.
hence 2^n = 1024 is sufficient meaning n = 10.
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