Question

Question 2.

JJ Painting Company is a well known construction contractor in the Boston area. The company was established in 2001, and they specialize in exterior painting. Management believes that the paint coating thickness is directly correlated with paint drying time. They have conducted a study to uncover the relationship between coating thickness and drying time.

Below are the results of their study.

Coating Thickness (mm) 18.18 8.07 20.65 2.96 22.45 22.01 9.4 15.22 4.8 2.86 13.3 20.71 3.37 5.14 22.1 9.15 13.18 15.37 16.44 16.48 25.05 7.77 21.2 6.36 3.59 20.39 18.68 25.86 8.26 13.73 20.13 24.82 9.03 12.48 18.61 2.73 21.63 12.38 24.14 24.31 6.18 8.9 11.35 2.12 23 21.09 24.33 13.82 5.65 7.5 8.47 11.82 1.97 20.01 22.9 13.06 20.94 11.43 14.85 22.13 14.3 24.38 14.03 13.51 10.94 19.58 15.71 16.61 17.11 4.55 15.36 25.93 18.18 3.63 3.77 15.82 1.79 17.28 13.88 24.32 21.28 3.79 17.3 13.11 16.48 8.16 11.98 16.67 23.82 19.64 15.14 20.67 1.73

Drying Time (s) 165.36 50.26 243.27 109.24 325.2 251.41 157.8 230.46 70.47 102.73 217.76 248.95 132.2 23.98 250.54 157.94 183.48 177.54 213.79 171.85 257.97 97.29 262.48 102.71 101.51 259.47 217.13 386.07 56.37 200.39 277.89 233.14 117.34 164.91 245.63 73.63 288.67 130.85 383.72 274.85 56.36 164.6 222.11 124 344.38 306.98 325.71 164.7 96.34 125.71 114.13 141.31 91.78 211.93 215.83 210.06 291.83 181.75 160.37 323.47 202.83 222.66 169.96 154.28 159.66 264.38 126.74 171.31 183.9 44.65 157.67 345.6 246.75 65.85 175.58 243.08 16.57 224.06 183.99 235.78 218.82 156.49 213.65 162.88 142.51 154.52 197.59 185.4 348.92 242.69 191.03 166.75 62.33

Regress the coating thickness against the paint drying time.

Based on this analysis, how much more time in seconds, will the paint take to dry, if coating thickness is increased by 1 mm. ?(Write your answer as a number with at least 2 decimal places)

Answer 1

using excel data analysis tool pak for regression,we get following output:-

Simple Linear Regression Analysis
Regression Statistics
Multiple R	0.8629
R Square	0.7446
Adjusted R Square	0.7418
Standard Error	41.4258
Observations	93
ANOVA
	df	SS	MS	F	Significance F
Regression	1	455361.8005	455361.8005	265.3475	0.0000
Residual	91	156164.7494	1716.0961
Total	92	611526.5499
	Coefficients	Standard Error	t Stat	P-value	Lower 95%	Upper 95%	Lower 95%	Upper 95%
Intercept	45.3408	9.7809	4.6356	0.0000	25.9122	64.7693	25.9122	64.76930
Coating Thickness (mm)	9.9717	0.6122	16.2895	0.0000	8.7557	11.1876	8.7557	11.18765

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so, regression equation is

drying time(s)=9.9717*coating thickness(mm)+45.3408

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Based on this analysis, how much more time in seconds, will the paint take to dry, if coating thickness is increased by 1 mm.

answer:9.97 seconds