- Step 1: Calculate total sales: A = $20 + 25 + 30 + 35 = 110$, B = $15 + 20 + 25 + 30 = 90$, C = $10 + 15 + 20 + 25 = 70$, D = $25 + 30 + 35 + 40 = 130$.
- Step 2: Average sales = Total $\div$ 4. For A: $110 \div 4 = 27.5$, B: $90 \div 4 = 22.5$, C: $70 \div 4 = 17.5$, D: $130 \div 4 = 32.5$.
- Step 3: Compare: $27.5$, $22.5$, $17.5$, $32.5$. Product D is highest.
- Step 4: Verify D: $25 + 30 + 35 + 40 = 130$, $130 \div 4 = 32.5$.
- Step 5: Check options: Option (4) is Product D, which matches.
- Step 6: Ensure no miscalculation in sums or division.