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.
1-Find E(S)
2-Find SE(S)
3-Find (no approximations, please) P(S=0)

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.
1-Find E(S)
2-Find SE(S)
3-Find (no approximations, please) P(S=0)

fibonaccichick666 · Answer

so what is the probability that they get the first question right?

anonymous · Answer

1/2

fibonaccichick666 · Answer

and just the next questions probability?

anonymous · Answer

can any one reply

anonymous · Answer

can any one ans for 2nd question SE(S)

nurali · Answer

@CarlosGP Find SE(S)

nurali · Answer

Thanks @CarlosGP ur answer is right thanks

dan815 · Answer

what does E(S) mean and SE(S) mean

anonymous · Answer

Hi!

E(S)=0 - correct
SE(S)=4.4721359 - correct

for P(S=0) - please to try "0.1762" - for this one i am not shure

nurali · Answer

0.1762 is correct answer.