Calculating Seasonal Indices for Monthly Sales

In a recent analysis of monthly sales data for XYZ Corporation, an analyst observed that sales peaked during the holiday season, specifically in December, and reached their lowest point in February. The analyst is interested in understanding the seasonal effects on sales to better predict future performance. They decided to compute the seasonal indices based on the sales data gathered from the last three years.

If the average monthly sales for December is $120,000 and for February is $80,000, while the average monthly sales across the entire year is $100,000, what are the seasonal indices for December and February?

Use the formula for calculating the seasonal index: $$ ext{Seasonal Index} = rac{ ext{Average Monthly Sales of the Month}}{ ext{Average Monthly Sales for the Year}}$$