18/24 can both be divided by 6, so it's 3/4
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
It would be 22 x 3.14 = 69.08 i’m pretty sure lolol sorry if i’m wrong
Remember that, for independent events, the probability that both occurr is the product of the individual probabilities.
a) Probability of being contacted: 78% = 0.78
Probaility of refusing: 1 - 22% = 1 -0.22 = 0.78
Combined probability: 0.78*0.78 = 0.6084
b) The probability of failing to contact or making contact and not geeting them to agree 1 - the probability of contacting and getting them to agree.
The probabilityof contacting and getting them to agree is 0.78*0.22 = 0.1716
The the answer to this question is 1 - 0.1716 = 0.8284