Verified answer

use transparent ruler for better result

# try drawing a straight line between the points on the graph, such that among scattered points one # compensate for other.

# there is no exact way to draw "best fit line"

# so, if sometime one reading has vast different than other readings then you can exclude it, by mentioning it as ommited.

# to find the slope, try finding two points that give exact value of coordinate on the best fit line

# draw a rt. angled triangle with dotted line taking those points as hypotenuse

# now using slope(m)= (y2-y1)/(x2-x1) find the slope of the best fit line.

Too much to describe here, but check this out, it'll give you the formulas you need:

http://stattrek.com/AP-Statistics-1/Regression-Exa...