There are "n" True False questions in the paper and the student has to

Question

There are "n" True False questions in the paper and the student has to mark either true or false. What is the minimum value of n for which probability of all true is less than 1/1000?

(A) 8
(B) 9
(C) 10
(D) 11
(E) 12

Archit3110 · Answer

P of true or false would be 1/2
target find value of n such that ( 1/2)^n<1/1000
n=10 ; (1/2)^10 ; 1/1024
1/1024<1/1000
option C

Kinshook · Answer

Given: There are "n" True False questions in the paper and the student has to mark either true or false. 
Asked: What is the minimum value of n for which probability of all true is less than 1/1000?

Probability of n all true = (1/2)^n < 1/1000
n = 10

IMO C

flippedeclipse · Answer

The crux of this question is that there are two possible outcomes - true or false - so this functions just like a coin flip. We're thus looking for a value for n where:

\frac{1}{2^n}=\frac{1}{1000}

The question becomes: "what power of 2 is the first to be greater than 1000?" Answer to that is  2^{10}=1028 , thus C.

There are "n" True False questions in the paper and the student has to

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