math
posted by tms .
In a population of 10,000 adults, 20% are smokers. A simple random sample of 600 of the adults is drawn.
a)The SE of the number of smokers in the sample is closest to
9.45
9.5
9.55
9.6
9.65
9.7
9.75
9.8
9.85
9.9
b)The chance that there are fewer than 115 smokers in the sample is closest to (pick the best of the options below, even if you can calculate the probability more accurately)
10%
20%
30%
40%
50%
60%
70%
80%
90%

SE=9.5
chance=30% 
and the Expected smoker #?

120

thanks

Can you give the steps that led to these answers?