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2.2.2 Scatter diagrams and correlation

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Question 34

A chemical engineer monitors the efficiency of an industrial reactor. Each batch begins with 250 kg of a liquid solvent. Over n=10n=10n=10 trial runs, the engineer records the mean operating temperature, xxx ∘C^\circ\text{C}∘C, and the mass of solvent that evaporates, y kgy\text{ kg}y kg. The following summary statistics are obtained:

∑x=850,∑y=120,∑xy=10425,Sxx=650,Syy=115 \sum x = 850, \quad \sum y = 120, \quad \sum xy = 10425, \quad S_{xx} = 650, \quad S_{yy} = 115 ∑x=850,∑y=120,∑xy=10425,Sxx​=650,Syy​=115
a.

Calculate the product moment correlation coefficient between x x\,x and yyy.

[3]
b.

The mass of liquid solvent remaining in the reactor at the end of each run is w kgw\text{ kg}w kg. (i) Write down an equation for w w\,w in terms of yyy. (ii) State the value of the product moment correlation coefficient between w w\,w and yyy.

[2]
c.

State the value of the product moment correlation coefficient between x x\,x and www.

[1]

2.2.2 Scatter diagrams and correlation Questions

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  3. /2.2.2 Scatter diagrams and correlation