Answer: 1,400

**Step-by-step calculation:** 1. **Sort the data in ascending order:** - 2,600 (Week 5) - 2,700 (Week 3) - 2,800 (Week 2) - 3,800 (Week 1) - 4,300 (Week 6) - 9,900 (Week 4) 2. **Calculate Q₁ (first quartile - 25th percentile):** - Position = α × n = 0.25 × 6 = 1.5 - Since 1.5 is not an integer, we average the 1st and 2nd data points - Q₁ = (2,600 + 2,700) ÷ 2 = 2,650 3. **Calculate Q₃ (third quartile - 75th percentile):** - Position = α × n = 0.75 × 6 = 4.5 - Since 4.5 is not an integer, we average the 4th and 5th data points - Q₃ = (3,800 + 4,300) ÷ 2 = 4,050 4. **Calculate IQR (Interquartile Range):** - IQR = Q₃ - Q₁ = 4,050 - 2,650 = 1,400 **Why other options are incorrect:** - **A (1,260):** Incorrect calculation, possibly using wrong quartile positions - **B (1,542):** Incorrect calculation, possibly not averaging properly - **C (1,475):** Incorrect calculation, possibly using different quartile estimation method The interquartile range (IQR) measures the spread of the middle 50% of the data and is less sensitive to outliers than the range.

Author: Nikitesh Somanthe