1. **Stating the problem:** We have sales data for 7 weeks for each weekday. We want to find the seasonal index for Monday, Wednesday, and Friday, and then use the forecast for Week 8 total sales to estimate sales for Tuesday in Week 8. 2. **Understanding seasonal index:** The seasonal index for a day measures how that day's sales compare to the average sales for the week. It is calculated as: $$\text{Seasonal Index for a day} = \frac{\text{Average sales on that day over weeks}}{\text{Average total sales per day over all days and weeks}}$$ 3. **Calculate total sales for each week:** Week 1: $43+26+15+25+26=135$ Week 2: $48+39+19+29+24=159$ Week 3: $46+24+17+28+23=138$ Week 4: $39+29+23+28+25=144$ Week 5: $30+34+12+20+26=122$ Week 6: $42+26+23+27+28=146$ Week 7: $46+21+19+20+30=136$ 4. **Calculate average total sales per week:** $$\frac{135+159+138+144+122+146+136}{7} = \frac{980}{7} = 140$$ 5. **Calculate average sales for each day over 7 weeks:** - Monday: $\frac{43+48+46+39+30+42+46}{7} = \frac{294}{7} = 42$ - Tuesday: $\frac{26+39+24+29+34+26+21}{7} = \frac{199}{7} \approx 28.43$ - Wednesday: $\frac{15+19+17+23+12+23+19}{7} = \frac{128}{7} \approx 18.29$ - Thursday: $\frac{25+29+28+28+20+27+20}{7} = \frac{177}{7} \approx 25.29$ - Friday: $\frac{26+24+23+25+26+28+30}{7} = \frac{182}{7} \approx 26.00$ 6. **Calculate seasonal indices:** - Monday: $\frac{42}{140} = 0.30$ - Wednesday: $\frac{18.29}{140} \approx 0.13$ - Friday: $\frac{26}{140} \approx 0.19$ 7. **Forecast sales for Tuesday in Week 8:** Given total forecast Week 8 sales = 139 ties. Using Tuesday's seasonal index: $$\text{Tuesday sales} = 139 \times \frac{28.43}{140} = 139 \times 0.2031 \approx 28.22$$ **Final answers:** - Seasonal index Monday: 0.30 - Seasonal index Wednesday: 0.13 - Seasonal index Friday: 0.19 - Tuesday sales forecast Week 8: 28.22