Use a noninteger mean, compare modal counts and audit finite-population assumptions

One question in a survey is as follows:

“Do you use Facebook during office hours at least once a day? Yes or No?”

It is known that on average, 7 out of 9 staff members answered “yes” to the above question.

For a random sample of 60 staff members,

(i) find the standard deviation of the number of staff members who answer “yes”,1 mark

(ii) find the probability that the number of staff members who answer “yes” exceeds the mean,3 marks

(iii) find the most probable number of staff members who answer “yes”,2 marks

(iv) state, with a reason, if the above answers are valid if the total number of staff members in the company is small.1 mark