A job applicant takes a 3-question true–false examination and guesses on each question. Let X be the number of right answers minus the number of wrong answers. Find p(x=2)

Question

A job applicant takes a 3-question true–false examination and guesses on each question. Let X be the number of right answers minus the number of wrong answers. Find  p(x=2)

amistre64 · Answer

binomial probability ...

anonymous · Answer

or just count.  there are 8 possible combinations and 3 of them contain 2 correct answers.

anonymous · Answer

oh no this is wrong wrong wrong. i should learn to read.

anonymous · Answer

right answers minus wrong answers.  there is no way this totals to 2.  so it is 0

anonymous · Answer

sometimes i am too dumb for words.  really helps to read the problem
@amistre x= # correct - # incorrect.  
how can that be 2?

anonymous · Answer

3 correct it is 3
2 correct it is 1
1 correct it is -1
0 correct it is -3

amistre64 · Answer

im working on it :)  my brain is like a steam locomotive; it takes a while to get going but it gets there eventually lol

anonymous · Answer

X is a random variable that takes on the values {-3,-1,1,3} only so P( X = 2) = 0

amistre64 · Answer

i concur ;)