19) (4pts) On a multiple choice test with 21 questions, each question has four possible answers, one of which is correct. For students who guess at all answers, find the standard deviation for the number of correct answers.
A) 15.5
B) 39.4
C) 3.9
D) 2

answer:

i havent taken the psat, but i have the sat, make sure to bring some snacks, because youre in there forever, 2 sharp number two pencils, an sat approved calculator, and maybe a jacket.   your phone and any books will be taken up, so don't try to bring them(but they will be given back at the end of the testing).   good luck!   i hope you do well!

answer:

explain more

explanation:

i don’t understand what you’re asking. elaborate more on that . also give me brainliest!