Answer:
A sample of 179 is needed.
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 
.
That is z with a pvalue of 
, so Z = 1.44.
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.
A previous study found that for an average family the variance is 1.69 gallon?
This means that 
If they are using a 85% level of confidence, how large of a sample is required to estimate the mean usage of water?
A sample of n is needed, and n is found for M = 0.14. So
Rounding up
A sample of 179 is needed.
Unsure of what you are asking!
But if the issue here is how to define a line segment, write what you do know and then reconsider "undefined terms."
A line segment is a straight line that connects a given starting point and given ending point.
If you consider a circle of radius 3 units, the radius can be thought of as the line segment connecting the center of the circle to any point on the circumference of the circle.
If the center of a given circle is at C(0,0) and a point on the circumference is given by R(3sqrt(2),3sqrt(2)), then AC is the line segment joining these two points. This line segment has length 3 and is in the first quadrant, with coordinates x=3sqrt(2) and y=3sqrt(2) describing the end point of the segment.
