In: Statistics and Probability
Statistics students in Oxnard College sampled 11 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) |
---|---|
761 | 66.27 |
855 | 57.85 |
681 | 60.67 |
658 | 42.06 |
218 | 24.26 |
587 | 44.09 |
973 | 72.11 |
925 | 68.75 |
672 | 45.04 |
426 | 28.82 |
243 | 28.01 |
A student calculates a linear model
yy = xx + . (Please show your answers to two decimal
places)
Use the model to estimate the cost when number of pages is
471.
Cost = $ (Please show your answer to 2 decimal places.)
Solution :
X | Y | XY | X^2 | Y^2 |
761 | 66.27 | 50431.47 | 579121 | 4391.7129 |
855 | 57.85 | 49461.75 | 731025 | 3346.6225 |
681 | 60.67 | 41316.27 | 463761 | 3680.8489 |
658 | 42.06 | 27675.48 | 432964 | 1769.0436 |
218 | 24.26 | 5288.68 | 47524 | 588.5476 |
587 | 44.09 | 25880.83 | 344569 | 1943.9281 |
973 | 72.11 | 70163.03 | 946729 | 5199.8521 |
925 | 68.75 | 63593.75 | 855625 | 4726.5625 |
672 | 45.04 | 30266.88 | 451584 | 2028.6016 |
426 | 28.82 | 12277.32 | 181476 | 830.5924 |
n | 10 |
sum(XY) | 376355.46 |
sum(X) | 6756.00 |
sum(Y) | 509.92 |
sum(X^2) | 5034378.00 |
sum(Y^2) | 28506.31 |
Numerator | 318535.08 |
Denominator | 343098.05 |
r | 0.9284 |
r square | 0.8619 |
Xbar(mean) | 675.6000 |
Ybar(mean) | 50.9920 |
SD(X) | 201.1207 |
SD(Y) | 14.1236 |
b | 0.0678 |
a | 5.2067 |
A student calculates a linear model
y = 0.07 x + 5.21
Cost = 0.0678 * 471 + 5.2067 = $37.14