I believe the answer for the first question is A. but not 100% sure, it's the only one I can figure out to be right.
The answer for the second question is C. 90% of 30 is 27.
I hope this helps.
S^2 is the only denominator. It is the least common denominator.
Answer:




Step-by-step explanation:
Given: The above data
Solving (a): Mean of each group
Mean is calculated as:




Solving (b): The sample size of each group
This is the number of rows in each group.
Hence:

Solving (c): Standard deviation (s)
This is calculated as:

So, we have:




Solving (d): Square root of n


Solving (e): SEM
This is calculated as:



