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Question 937105:
Jillian recorded how much fertilizer she gave her roses and the number of blooms they produced. What is a good line of best fit for the data?
http://www.usatestprep.com/modules/gallery/files/57/5757/5757.png
A. y - 8 = 1(x-4)
B. y - 8 = -1(x-4)
C. y - 8 = 4/3(x-4)
D. y - 8 = -4/3(x-4)
Found 2 solutions by Edwin McCravy, djreal 215:
Answer by Edwin McCravy(20056)   (Show Source):
You can put this solution on YOUR website! A. y - 8 = 1(x-4)
B. y - 8 = -1(x-4)
C. y - 8 = 4/3(x-4)
D. y - 8 = -4/3(x-4)
Those are all in point slope form
y - y1 = m(x - x1)
All four of them go though the point (4,8)
We can immediately rule out B and D because they have
a negative slope. Lines with a negative slope go downhill
to the right like this \. Your points go uphill
to the right, like this /.
So the correct choice is either A or C.
Hold a ruler or straight edge (or imagine holding one)
so that it goes through the point (4,8) and is as close
to as many of the points as you can get it. Pick the two
points that are the closest to the ruler or straight edge.
I picked (6,10) and (9,14).
Use the slope formula:
They have a slope of 
What do you know! That's exactly the slope of one of the
chices, C.
I didn't expect it to be exactly one of the slopes. It
just happened to be exact. I only expected it to be close.
Answer: C.
Edwin
Answer by djreal 215(1)  (Show Source):
You can put this solution on YOUR website! Those are all in point slope form
y - y1 = m(x - x1)
All four of them go though the point (4,8)
We can immediately rule out B and D because they have
a negative slope. Lines with a negative slope go downhill
to the right like this \. Your points go uphill
to the right, like this /.
So the correct choice is either A or C.
Hold a ruler or straight edge (or imagine holding one)
so that it goes through the point (4,8) and is as close
to as many of the points as you can get it. Pick the two
points that are the closest to the ruler or straight edge.
I picked (6,10) and (9,14).
Use the slope formula:
They have a slope of %2814-10%29%2F%289-6%29+=+4%2F3
What do you know! That's exactly the slope of one of the
chices, C.
I didn't expect it to be exactly one of the slopes. It
just happened to be exact. I only expected it to be close.
Answer: C.
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