Carpet City orders Soft Shag from the Carpet City Mill. The production rate at the mill is 1200 yards per day, and the mill operates 260 days per year. The annual carrying cost is \[tex]$0.63 per yard, the order cost is \$[/tex]425, and the lead time for receiving an order is 7 days.

a) Use a 3-month moving average to forecast a value for Month 9. Use this forecast as the demand, with a daily demand assuming this is for September—a 30-day month.

b) Compute the optimal order quantity, the total monthly and annual minimum inventory cost, and the reorder point.

\begin{tabular}{|c|c|c|}
\hline
Month & Demand & 3-Month Moving Average \\
\hline
1 & 8,000 & \\
\hline
2 & 12,000 & \\
\hline
3 & 7,000 & \\
\hline
4 & 9,000 & 9,000 \\
\hline
5 & 15,000 & 9,333 \\
\hline
6 & 11,000 & 10,333 \\
\hline
7 & 10,000 & 11,667 \\
\hline
8 & 12,000 & 11,000 \\
\hline
9 & & 11,000 \\
\hline
\end{tabular}



Answer :

Sure! Let's go through the problem step-by-step:

### Given Data:
- Production rate per day: 1200 yards
- Operating days per year: 260 days
- Annual carrying cost: \$0.63 per yard
- Order cost: \$425
- Lead time: 7 days
- We assume a 30-day month for September.

### Step 1: 3-Month Moving Average

To calculate the 3-month moving average for Month 9, we average the demands of Months 6, 7, and 8:

Month 6: 11,000 yards
Month 7: 10,000 yards
Month 8: 12,000 yards

3-Month Moving Average for Month 9:
[tex]\[ \text{Forecast for Month 9} = \frac{(11,000 + 10,000 + 12,000)}{3} = \frac{33,000}{3} = 11,000 \text{ yards} \][/tex]

This is the forecasted demand for Month 9.

### Step 2: Daily Demand

To find the daily demand for September (a 30-day month):

[tex]\[ \text{Daily Demand} = \frac{\text{Forecasted Monthly Demand (Month 9)}}{30} = \frac{11,000 \text{ yards}}{30 \text{ days}} = 366.67 \text{ yards per day} \][/tex]

### Step 3: Annual Demand

Given the daily demand, we can calculate the annual demand assuming 260 operating days:

[tex]\[ \text{Annual Demand} = \text{Daily Demand} \times \text{Operating Days} = 366.67 \text{ yards/day} \times 260 \text{ days} = 95,333.33 \text{ yards} \][/tex]

### Step 4: Optimal Order Quantity (EOQ)

The Economic Order Quantity (EOQ) is given by the formula:

[tex]\[ \text{EOQ} = \sqrt{\frac{2DS}{H}} \][/tex]

where:
- \(D\) is the annual demand,
- \(S\) is the order cost (\$425),
- \(H\) is the annual carrying cost (\$0.63).

Plugging in the values:

[tex]\[ \text{EOQ} = \sqrt{\frac{2 \times 95,333.33 \text{ yards} \times \[tex]$425}{\$[/tex]0.63}} \approx 11,341.27 \text{ yards}
\][/tex]

### Step 5: Total Inventory Cost

The total annual inventory cost consists of the ordering cost and the carrying cost.

1. Ordering Cost:
[tex]\[ \text{Ordering Cost} = \frac{D}{\text{EOQ}} \times S = \frac{95,333.33 \text{ yards}}{11,341.27 \text{ yards}} \times \[tex]$425 \approx \$[/tex]3,572.49
\][/tex]

2. Carrying Cost:
[tex]\[ \text{Carrying Cost} = \frac{\text{EOQ}}{2} \times H = \frac{11,341.27 \text{ yards}}{2} \times \[tex]$0.63 \approx \$[/tex]3,572.49
\][/tex]

The total annual inventory cost:

[tex]\[ \text{Total Annual Cost} = \text{Ordering Cost} + \text{Carrying Cost} \approx \[tex]$3,572.49 + \$[/tex]3,572.49 = \$7,145
\][/tex]

The total monthly cost:

[tex]\[ \text{Monthly Cost} = \frac{\text{Total Annual Cost}}{12} \approx \frac{\[tex]$7,145}{12} \approx \$[/tex]595.42
\][/tex]

### Step 6: Reorder Point

The reorder point is calculated by multiplying the daily demand by the lead time:

[tex]\[ \text{Reorder Point} = \text{Daily Demand} \times \text{Lead Time} = 366.67 \text{ yards/day} \times 7 \text{ days} \approx 2,566.67 \text{ yards} \][/tex]

### Results Summarized:

- Forecasted demand for Month 9: 11,000 yards
- Daily demand: 366.67 yards/day
- Optimal order quantity (EOQ): 11,341.27 yards
- Total annual inventory cost: \$7,145
- Total monthly inventory cost: \$595.42
- Reorder point: 2,566.67 yards

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