On a 9 question True-or-False test you randomly guess all the answers. What is the probability that you get all 9 answers wrong?
a)1/2
b)511/512
c)8/9
d)1/512

Question

On a 9 question True-or-False test you randomly guess all the answers. What is the probability that you get all 9 answers wrong?
a)1/2
b)511/512
c)8/9
d)1/512

parthkohli · Answer

Probability that you will get a question wrong: 1/2
Probability that you get 9 questions wrong: 1/2 * 1/2 * 1/2 - 9 times..
$ \color{Black}{\Rightarrow  \Large ({1 \over 2})^{9}}$
$ \color{Black}{\Rightarrow \Large {1 \over {2^9}} }$

anonymous · Answer

I don't get it sorry.. I know I have to multiply 1/2 nine times but I can't get the answer! can you please help me. What is the answer?

ganeshie8 · Answer

$$2^{9} = 512$$

anonymous · Answer

Thanks!