Consider the following portion of data on the response variable y and the explanatory variable x.

t................. y............... x

1........... 27.96............ 29.88

2........... 30.15............ 21.07

⋮...................... ⋮....................... ⋮

12........... 24.47.......... 26.41

a. Estimate yt = β0 + β1xt−1 + εt and yt = β0 + β1xt−1 + β2xt−2 + εt .

b. Use the appropriate model to make a one-stepahead forecast (t = 13) for y.