Using the table Gasoline Sales Time Series, calculate the forecast for gasoline sales (in thousands) for Week 13 using a three day moving average.

Gasoline Sales Time Series

Week Sales (000s of gallons)

1 17

2 21

3 19

4 23

5 18

6 16

7 20

8 18

9 22

10 20

11 15

12 22

A.18.50

B.19.00

C.19.50

D.20.00