Aquiz consists of 10 multiple-choice questions, each with 5 possible answers. for someone who makes random guesses for all of the answers, find the probability of passing if the minimum passing grade is 60 %. p(pass) =

"Passing" would entail getting 6 or more answers correct.

One way in which to calculate this probability would be to use the
"binomcdf(" function available on TI calculators.

binomcdf(10,0.2,0) produces a list of cumulative binomial probabilities for n=0 to n=10.  We take the 6th such sum; it is 0.9936.  This is the probability that the student, choosing answers at random, will get 5 or fewer answers right.  (In other words, it's awfully hard to guess your way thru a multiple-choice test.)

Subtracting 0.9936 from 1.0000 produces the probability 0.0064  This is the probability of getting 6 or more questions right by guessing.