Question: The number of days since the appearance of a tumour in an animal, and the size of the tumour, are shown below:

Days 14 16 19 21 23 26 28 30 33

Size(cm³) 1.25 1.90 4.75 5.45 7.53 14.5 16.7 21.0 27.1

Construct the best regression that you can find, and use the model to estimate the size of the tumour after 26 days.