In: Statistics and Probability
assume that random guesses are made for 7 multiple choice questions test, with 5 choices for each questions, so that there are n=7 trials, each with probability of success (correct) given by p=0.20 Find the probability of not correct answers
We have 5 choices for each.
p = probability of selecting correct choice = 0.20 ( out of 5 choice 1 choice is correct choice so 1/ 5 = 0.20)
n = total number of question (trials ) = 7
We use binomial distribution.
The probability of not correct answers means we have to find P (X = 0 )
We use formula
We plug the value of n= 7 and x = 0
! means factorial sign
0! is always 1 beacuse we can arrage 0 by 1 way
0! = 1
We use formula
So we get
Final answer :-
probability of not correct answers = 0.2097152