The data below show the volume of transactions(in hundreds ofthousands) in shares of a corporation over a period of 12 weeks. Using thesedata, estimate afirst-order autoregressivemodel, and use the fitted model to obtain forecasts of volume for the next 3 weeks.

Week Trading Volume

1 29.9

2 11.2

3 11.3

4 18.2

5 19.7

6 19.7

7 12.2

8 22.0

9 21.0

10 19.6

11 24.1

12 21.9

The estimatedfirst-order autoregressive model is

xt= 19.37+ (-0.06)xt-1

Calculate

x13=

x14=

x15=