In determining monthly seasonal indexes for petrol consumption, the sum of the 12 means for petrol consumption as a percentage of the moving average is 1230. To get the seasonal indexes, each of the 12 monthly means is to be multiplied by:
A)1200 / 1230.
B)1230 / 1200.
C)(1230 + 1200) / 2.
D)(1230 + 1200) / 12.

Question

Quizplus · Accepted Answer

To normalize the seasonal indexes so that their sum equals 1200 (100% for each month), each mean should be multiplied by 1200 / 1230 to adjust the total sum from 1230 to 1200.

In Determining Monthly Seasonal Indexes for Petrol Consumption, the Sum