Please help me, do not understand

Question

Assume that random guesses are made for 66 multiple-choice questions on a test with

55 choices for each​ question, so that there are n=6 ​trials, each with probability of success​ (correct) given by

p=0.20. Find the probability of no correct answers.

Answer 1

It is binomial p=1/5 = 0.2, N=6 k=5

(6 choose 5) (0.2)^5 ( 0.8) = 6 * (0.2)^5 ( 0.8) = 0.1536% is probability for 5 out of 6

No correct answers......

(6 choose 0) (0.2)^0 (0.8)^5 = 0.8^5 = 32.768%