Answer:
a.1.90 years
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.
In this question:

So

So the correct answer is:
a.1.90 years
Answer:
the answer is the first choice .
Answer:
D/About 18.85
Step-by-step explanation:
So, Using the Circle Circumfrince Formula:

There you go!
Hope this helps!
P.S. Stay Safe!
7+5=12 so it can be one of these 8+4=12, 9+3=12, 10+2=12, and 11+1=12.