Answer: $400 million

**Explanation:** A seasonal index of 1.8 means that Quarter 1 sales are 80% above the average quarterly sales (since an index of 1.0 represents the average). **Step 1: Calculate average quarterly sales** - Quarter 1 sales = $180 million - Seasonal index = 1.8 - Average quarterly sales = Quarter 1 sales ÷ Seasonal index = $180 million ÷ 1.8 = $100 million **Step 2: Calculate annual sales estimate** - Annual sales = Average quarterly sales × 4 quarters = $100 million × 4 = $400 million Therefore, the correct answer is **$400 million**. The provided explanation in the text confirms this calculation: "An index of 1.8 means that quarter 1 sales are 80% above the norm (average). Thus, each quarter has average sales worth $180,000,000 / 1.8 = $100,000,000. Therefore, the annual estimate = 4 * Quarter average = 4 * $100,000,000 = $400,000,000."

Author: Nikitesh Somanthe