A true-false test consists of 20 questions, each of which has one correct answer: true, or false. One point is awarded for every correct answer, but one point is taken off for each wrong answer. Suppose a student answers every question by guessing at random, independently of other questions. Let S be the student’s score on the test. Find SE(S)

Question

A true-false test consists of 20 questions, each of which has one  correct answer: true, or false. One point is awarded for every correct answer, but one point is taken off for each wrong answer. Suppose a student answers every question by guessing at random, independently of other questions. Let S be the student’s score on the test. Find SE(S)

dumbsearch2 · Answer

Does this help, in any way ? :) http://math.stackexchange.com/questions/383695/statistics-and-probability-sum

dumbsearch2 · Answer

I feel bad that the guy on the StackExchange only got one upvote! :p
upvote his answer maybe, to help :)

agent0smith · Answer

Yeah, someone asked me that question the other day, but I didn't remember and could not find that standard error formula. $$\Large SE = \sqrt{ \frac{ p(1-p) }{ n } }$$

agent0smith · Answer

@Nurali