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A jewelry firm buys semiprecious stones to make bracelets and rings. The supplie

ID: 347669 • Letter: A

Question

A jewelry firm buys semiprecious stones to make bracelets and rings. The supplier quotes a price of $8.20 per stone for quantities of 600 stones or more, $8.60 per stone for orders of 400 to 599 stones, and $9.10 per stone for lesser quantities. The jewelry firm operates 101 days per year. Usage rate is 19 stones per day, and ordering costs are $39.

a. If carrying costs are $2 per year for each stone, find the order quantity that will minimize total annual cost. (Do not round intermediate calculations. Round your final answer to the nearest whole number.)
  

Order quantity             stones

b. If annual carrying costs are 21 percent of unit cost, what is the optimal order size? (Do not round intermediate calculations. Round your final answer to the nearest whole number.)
  

Optimal order size             stones

c. If lead time is 3 working days, at what point should the company reorder? (Do not round intermediate calculations. Round your final answer to the nearest whole number.)
  

Reorder quantity             stones

Explanation / Answer

Given values:

For quantities (Q) > 600 stones, Price (P) = $8.20 per stone

(Q) = 400 to 599 stones, Price (P) = $8.60 per stone

(Q) < 400 stones, Price (P) = $9.10 per stone

Number of working days = 101 per year

Daily demand, d = 19 stones

Annual demand, D = 101 x 19 = 1919 stones

Ordering costs, Co = $39

Solution:

(a) Carrying costs, Ch = $2 per year

Total annual cost will be minimum at the Economic order quantitiy (EOQ). EOQ is determined using the below formula:

EOQ = 2DCo/Ch

where,

D = Annual demand

Co = Ordering costs

Ch = Carrying costs

Putting the given values in the above formula, we get;

EOQ = (2 x 1919 x 39)/2

EOQ = 273.57 or 274

Total annual cost will be minimum at order quantity of 274 stones

(b) Annual carrying cost = 21 percent of unit cost

Since, there are three different price slabs, the optimal order size will be determined for each price slab.

1) (Q) > 600 stones, Price (P) = $8.20 per stone:

Carrying cost, Ch = 21% of $8.20

Ch = $1.72

EOQ = 2DCo/Ch

EOQ = (2 x 1919 x 39)/1.72

EOQ = 294.99 or 295

EOQ = 295 stones

Not feasible, since EOQ falls below the applicable quantity slab of Q > 600.

2) (Q) = 400 to 599 stones, Price (P) = $8.60 per stone

Carrying cost, Ch = 21% of $8.60

Ch = $1.81

EOQ = 2DCo/Ch

EOQ = (2 x 1919 x 39)/1.81

EOQ = 287.57 or 288

EOQ = 288 stones

Not feasible, since EOQ falls below the applicable quantity slab of Q = 400 - 599.

3) (Q) < 400 stones, Price (P) = $9.10 per stone

Carrying cost, Ch = 21% of $9.10

Ch = $1.91

EOQ = 2DCo/Ch

EOQ = (2 x 1919 x 39)/1.91

EOQ = 279.94 or 280

EOQ = 280 stones (Feasible)

Optimal order size = 280 stones

(c) Lead time = 3 days

Reorder point is calculated as;

R = L x d

where,

L = Lead time

d = daily demand

R = 3 x 19

Reorder quantity = 57 stones

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