Answer:
c) (26.295, 28.705)
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 27.5 - 1.205 = 26.295 mi/gallon
The upper end of the interval is the sample mean added to M. So it is 27.5 + 1.205 = 28.705 mi/gallon
So the correct answer is:
c) (26.295, 28.705)
Answer:
I Think so 3 option is the correct answer of this question
Remark
You can use a formula to get the right answer. Otherwise you will use a lot of paper adding 100 numbers together.
Givens
A = 1
L = 100
n = 100 numbers to be added together. There are 100 numbers between 1 and 100 numbers inclusive.
Formula
Sum = (A + L)*n/2
Solution
Sum = (1 + 100)*100/2 Substitute in the givens. Add what is inside the brackets
Sum = (101) * 100 / 2 Divide by 2
Sum = 101* 50 Multiply
Sum = 5050 Answer