As water temperature increases, sodium nitrate (NaNO₃) becomes more soluble. The following table (103) gives the number of parts of sodium nitrate that dissolve in one hundred parts of water.

Temperature

(degrees Celsius), x           Parts Dissolved, y

0………………………………………           66.7

4………………………………………           71.0

10……………………………………..           76.3

15……………………………………..           80.6

21……………………………………..           85.7

29……………………………………..           92.9

36……………………………………..           99.4

51……………………………………..          113.6

68……………………………………..          125.1

Calculate the residuals, y₁ – ŷ ₁, . . . , y₉ – ŷ₉, and draw the residual plot. Does it suggest that fitting a straight line through these data would be appropriate? Use the following sums:

Xi =234 2y = 811.3 i-I i Xi = 10.144 Xiyi = 24,628.6 !