Hi
Excel will do your scatter plot as well as the Trend Line and R^2 automatically!
Calculating correlation coefficient: sqrt(R^2) using Excel...
X Y XY X^2 Y^2
1 10 10 1 100
2 15 30 4 225
3 25 75 9 625
4 30 120 16 900
5 40 200 25 1600
sum 15 120 435 55 3450
sum squared 225 14400
Correlation(r) = NΣXY - (ΣX)(ΣY) / Sqrt([NΣX^2 - (ΣX)^2][NΣY^2 - (ΣY)^2])
r = (5*435 - 15*120)/sqrt([5*55-225][5*3450-14400]) =