seasonal variation

In a time series analysis, the multiplicative model is used to forecast sales and the following seasonal variations
apply:
Quarter 1 2 3 4
Seasonal variation 1.2 1.3 0.4 ?
The actual sales values for the first two quarters of 2006 were:
Quarter 1: $125,000
Quarter 2: $130,000

27.17 What is the seasonal variation for the fourth quarter?
A –2.9
B 0.9
C 1.0
D 1.1

i dont understand how to find this? please help:)