Probability: Deceit Someone please help me. My online statistics class isn't able to give me the help i need to confidently perform this problem.

85% of those trained were able to pass the polygraph examination even when guilty of a crime. suppose that a random sample of 9 students are told a "secret" and then given instructions on how to pass the polygraph examination without revealing the secret. what is the probability that: a) all the students are able to pass the polygraph examination? b) more than half the students are able to pass the polygraph examination? c) no more than four of the students are able to pass the polygraph examination? d) all the students fail the polygraph examination?

I put it into the calculator with binompdf. My n=9, probability of success=.85. For part (a) i got .23162. Am I doing this right?