Question

# Statistics students in Oxnard College sampled 9 textbooks in the Condor bookstore and recorded the number...

Statistics students in Oxnard College sampled 9 textbooks in the Condor bookstore and recorded the number of pages in each textbook and its cost. The bivariate data are shown below:

Number of Pages (xx) Cost(yy)
347 42.29
714 77.98
576 54.32
485 52.95
397 53.79
828 69.96
333 42.31
891 81.37
615 66.05

A student calculates a linear model
Use the model to estimate the cost when number of pages is 426.

Solution:

 X Y XY X^2 Y^2 347 42.29 14674.63 120409 1788.4441 714 77.98 55677.72 509796 6080.8804 576 54.32 31288.32 331776 2950.6624 485 52.95 25680.75 235225 2803.7025 397 53.79 21354.63 157609 2893.3641 828 69.96 57926.88 685584 4894.4016 333 42.31 14089.23 110889 1790.1361 891 81.37 72500.67 793881 6621.0769 615 66.05 40620.75 378225 4362.6025

 n 9 sum(XY) 333813.58 sum(X) 5186.00 sum(Y) 541.02 sum(X^2) 3323394.00 sum(Y^2) 34185.27 Numerator 198592.50 Denominator 212445.46 r 0.9348 r square 0.8738 Xbar(mean) 576.2222 Ybar(mean) 60.1133 SD(X) 169.9661 SD(Y) 11.8604 b 0.0658 a 22.1706

Y hat = a + bX

= 22.17 + 0.07 X

Cost = 22.17 + 0.07 * 426

= \$51.99

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