Question

Find the indicated probability, A multiple choice test has 8 questions each of which has 4 possible answers, only one of which is correct. Il Judy, who forgot to study for the test guesses on all questions, what is the probability that she will answer exactly 3 questions correctly?

Answer 1

Page : Date : Given number of trial (n) = 8 probability for each comect answer Here, 9) Given trial results in only two mutually exclusive outcome ; e [conect answer & incorrect answer] b) Here n=8 is fired c) Also the probability cp) is constant for each conect from this above information we can say that meeltiple Test follows Binomial Dis hobution, let X be the number of correct answer answert P[x = x 7 = B(x ; n, pl = nc n p" (1-P) 기 B (*; 8, 1/4) =(8c a 21; :0,1,2-.--8 4 P+qiell p-1 ; otherwise o 3 8c 3 5 probability that the "Judy will answer exactly 9 questions conecty is P C7=3) (4) (क) = 8+7+4+5! (el 3+2+1+5) (215 :: p(x-3) = 0.2076416016 "Probability that Judy will answer exqchy g questions conectly is 56+ (1) 0.2076