Answer:
c) .22
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:

Then



Answer:
13.32cm squared
Step-by-step explanation:
Area of triangle is B X H X0.5
The discriminant is b²-4ac
when the discriminant is 0, there is only one solution.