Linear Regression

Question

Statistics students in Oxnard College sampled 10 textbooks in the Condor bookstore and recorded the number of pages in each textbook and its cost. The data are shown below:

Number of Pages (xx)Cost(yy)
928	77.24
882	70.56
662	47.96
402	27.16
336	31.88
434	35.72
502	33.16
421	36.68
273	15.84
669	66.52

A student calculates a linear model using technology (Statistics Calculator or Computer)

ˆyy^ = Incorrect xx + Incorrect. (Please show your answers to two decimal places)

Use the model to estimate the cost when number of pages is 830.

Cost = $Incorrect (Use the linear model with yor rounded coefficients and then round your answer to 2 decimal places.)

Answer 1

If you have a TI-84, put this data in a list by pushing the "stat" button then "Edit:". Type in the number of Pages into L1 and the Cost in L2. Once entered, go back to the main screen and calculate the linear regression values by pushing "stat" then "CALC" then "4: LinReg (ax+b)". Make sure Xlist is L₁ and Ylist is L₂ then highlight "Calculate" and push "enter"

You should get the following:

y=ax+b

a=0.0871921791

b=-3.762171485

If you have stat diagnostics turned on you will also get:

r² = 0.9146419636

r = 0.9563691566

In your question, y = ___x + ____ the first blank is the "a" and the 2nd blank is the "b". To predict the cost for 830 pages, plug in x = 830 into your equation.

If you do NOT have a TI-84, you can use desmos in a similar way. If you need help with that, let me know.