Hydrogen content is conjectured to be an important factor in porosity of aluminum alloy castings. The article “The S

Reduced Pressure Test as a Measuring Tool in the Evaluation of Porosity/Hydrogen Content in A1–7 Wt Pct Si-10 Vol Pct SiC(p) Metal Matrix Composite” (Metallurgical Trans., 1993: 1857–1868) gives the accompanying data on x content and y gas porosity for one particular measurement technique.

Minitab gives the following output in response to a Correlation command:
Correlation of Hydrcon and

a. Test at level .05 to see whether the population correlation coefficient differs from 0.

b. If a simple linear regression analysis had been carried out, what percentage of observed variation in porosity could be attributed to the model relationship?