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There are four grocery stores in your neighborhood and you are the manager of on

ID: 3273778 • Letter: T

Question

There are four grocery stores in your neighborhood and you are the manager of one of them. A customer has returned a relatively expensive and damaged item for a refund without a sales slip. You know that the item is carried by all four stores and you account for 65% of the sales of the item in the neighborhood. You are more careful in screening these items as you buy them, hence usually only have 0.25% defectives in your inventory. Your estimate of % defectives at your competitors is 0.3%

What is the chance that the customer bought the item from you?

If you do not give a refund, your eventual loss of good will is $70 if the person did buy the item from you. There is no loss if it was not bought from you. The future earnings from this customer are increased by $10 if he bought it from you and $40 if he did not. The cost of the refund to you is $50. On a mathematical basis, should you make the refund?

Explanation / Answer

Probability that the customer bought the item from our shop is computed as:

= Probability that the customer bought a defective one from our shop / Probability that a defective item is bought from any shop

= (0.65*0.0025)/ (0.65*0.0025 + 0.35*0.003)

= 0.6075

Therefore 0.6075 is the required probability that the customer bought the item from us.

Expected value given that the refund is made = -50 + 0.6075*10 + 40*(1-0.6075) = -28.225

Expected value given that the refund is not done = - 0.6075*70 = -42.525

Therefore the refund should be done.

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