Answer:
126 students are first-year students.
Step-by-step explanation:
The answer is 126 because 30% of 420 is 126.
P.S Can I have brainliest?
Answer:
The 95% confidence interval for μ for the given situation is between 87.49 and 94.51.
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 margin of error M as such

In which
is the standard deviation of the population and n is the size of the sample.

The lower end of the interval is the sample mean subtracted by M. So it is 91 - 3.51 = 87.49
The upper end of the interval is the sample mean added to M. So it is 91 + 3.51 = 94.51
The 95% confidence interval for μ for the given situation is between 87.49 and 94.51.
Answer: 3.78
Step-by-step explanation: