Answer:
I think the answer is C.) -3.2 > -4.1
We can simplify across between the 5 and the 50 and also between the 42 and the 3.
Memorize the definition of standard deviation: the sd is the square root of the average of the squared deviations of the mean. Wow. Let's do it.
Step 1. First we need the mean. That's easy. Add them up and divide by the count. Check if you get 16.88/5 = 2.81333.
Step 2. Now we're going to subtract this from each of the values, and square the result. Don't worry about negative signs, the squaring will get rid of those. Example for the first number:
(1 - 2.813)^2 = 3.29
The list of numbers I get is (rounded, in reality round as little as possible):
3.29, 2.60, 1.41, 2.35, 1.66, 6.18
Step 3: Add them all up. I get 17.49.
Step 4: Divide by the count of numbers. 17.49/6 = 2.91
Step 5: Take the square root from this result. SQRT(2.91) = 1.707305
TIP: Use excel to do all these steps, then run the set of numbers through Excel's built-in sd function (called STDEV.P) and see that you get the same result!
Answer:
The sample mean is
b.3.55
The margin of error is
0.32
Step-by-step explanation:
Deep explanation about a confidence interval
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 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 mean subtracted by M. So it is 6.4 - 0.3944 = 6.01 hours.
The upper end of the interval is the mean added to M. So it is 6.4 + 0.3944 = 6.74 hours.
In this problem:
The deep explanation is not that important.
We just have to recognize that the interval has a lower end and an upper end. The distance from both the upper and the lower end to the mean is M. This means that the sample mean is the halfway point between the lower end and the upper end.
The margin of error is the distance of these two points(lower and upper end) to the mean.
In our interval
Lower end: 3.23
Upper end: 3.87
Sample mean
So the correct answer is:
b.3.55
The margin of error is
3.87 - 3.55 = 3.55 - 3.23 = 0.32
X=cubic root 2/27
Glad to help
