this is about a multiple-choice test in which each question has 4 choices only one of which is correct. Assume that 9 questions are answered by guessing randomly. What is the probability of getting exactly 6 correct answers?

Question

anonymous · Answer

bernoulli trials for this one

$$p=\frac{1}{4}, 1-p=\frac{3}{4}, n = 9, k = 6$$

anonymous · Answer

$$P(x=6)=\dbinom{9}{6}(.25)^6(.75)^3$$ reaoning that there are 6 correct, 3 incorrect and 
$$\dbinom{9}{6}=84$$ different arrangements of 6 right and 3 wrong

anonymous · Answer

rest requires a calculator, you good from here?

anonymous · Answer

I believe so :) thank you again satelite