Bernoulli/Binomial Distributions

There is this one part of a problem I'm having trouble setting up...

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On a six-question multiple-choice test there are five possible answers for each question, of which one is correct (C) and four are incorrect (I). If a student guesses randomly and independently, find the probability of

For this, I let if answer is correct, and if the answer is incorrect.

Quote:

**(a)** Being correct only on questions 1 and 4 (i.e. C, I, I, C, I, I)

I'm not quite sure on how to set this part up, any hints would be appreciated.

Quote:

**(b)** Being correct on two questions

I think this would be ...but I'm not quite sure.

I'd appreciate any input! (Nod)

--Chris