Hi
A quiz consists of 20 multiple-choice questions, each with 5 possible answers
P(passing) if the minimum passing grade is 70 %. |that is, 14 or more correct
Note: The probability of x successes in n trials is:
P = nCx*where p and q are the probabilities of success and failure respectively.
In this case p = 1/5 = .2 and q = .8
nCx =
For example:
P(x = 14) = 30C14(.2)^14(.8)^6 = 38,760(.2)^14(.8)^6 = .0000016647
P(x ≥ 14) = P(14)+P(15)+P(16)+P(17)+P(18)+P(19)+P(20) = .000001845