Question

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 ( x ) Cost( y ) 562 67.58 482 68.38 535 70.15 934 107.06 271 31.39 543 66.87 219 35.71 786 93.74 882 103.38 A student calculates a linear model y = x + . (Please show your answers to two decimal places) Use the model to estimate the cost when number of pages is 639. Cost = $ (Please show your answer to 2 decimal places.)

Answer 1

Sum of X = 5214
Sum of Y = 644.26
Mean X = 579.3333
Mean Y = 71.5844
Sum of squares (SS_X) = 498076
Sum of products (SP) = 52720.5067

Regression Equation = ŷ = bX + a

b = SP/SS_X = 52720.51/498076 = 0.11

a = M_Y - bM_X = 71.58 - (0.11*579.33) = 10.26

ŷ = 0.11X + 10.26

Now or x=639, ŷ = (0.11*639) + 10.26=80.55