Answer: There were 32 teachers.
Step-by-step explanation:
(215 - 23)/6 = amount of teachers
215 - 23 = 192
192/6 = 32
We would need a sample size of 560.
We first calculate the z-score associated. with this level of confidence:
Convert 95% to a decimal: 95% = 95/100 = 0.95
Subtract from 1: 1-0.95 = 0.05
Divide by 2: 0.05/2 = 0.025
Subtract from 1: 1-0.025 = 0.975
Using a z-table (http://www.z-table.com) we see that this is associated with a z-score of 1.96.
The margin of error, ME, is given by:

We want ME to be 4%; 4% = 4/100 = 0.04. Substituting this into our equation, as well as our proportion and z-score,
Answer:
yes, yes
Step-by-step explanation:
B={1,2,3} it doesn't matter if it has ten 2's or one!
so A=B and A⊆B
Answer:
Step-by-step explanation:
C ?
Sorry, don't have time to do them right now but I know who does!
http://www.wolframalpha.com/widgets/view.jsp?id=ae438682ce61743f90d4693c497621b7
Just plug in 2 at a time.