It is a trick question 13+13 DOES equal 26
Answer:
Mean = 21.3
Standard Deviation = 2.48
Step-by-step explanation:
We are given the following in the question:
p = 71% = 0.71
Sample size, n = 30
We have to find the mean and the standard deviation of those that wear glasses.

Thus, the mean of those who wear glasses is 21.3

Thus, the standard deviation of those who wear glasses is 2.48
Answer A is the only one that seems to make sense to me id choose A
Answer:
A sample size of 35 is needed.
Step-by-step explanation:
We have that to find our
level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Ztable as such z has a pvalue of
.
So it is z with a pvalue of
, so 
Now, find the width W as such

In which
is the standard deviation of the population and n is the size of the sample.
How large must the sample size be if the width of the 95% interval for mu is to be 1.0:
We need to find n for which W = 1.
We have that
, then
. So





Rounding up
A sample size of 35 is needed.
root 30 ..................