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Question

By selling a watch for Rs. 2,000, a shopkeeper loses 20%. How much would he gain or lose by selling it for Rs. 3,000?

This question was previously asked in
SSC CGL 2023 (Tier-II) Paper 1 Previous Year Paper (26-Oct-2023) (Shift-1)
The correct answer is

20% gain

Understanding the Watch Selling Problem

This problem involves calculating profit and loss percentages related to the selling price and cost price of a watch. We are given the selling price at which a loss occurred and need to find the gain or loss percentage if the watch is sold at a different price.

To solve this, we first need to determine the original cost price (CP) of the watch. Once we know the CP, we can compare it to the new selling price (SP) of Rs. 3,000 to find the gain or loss and then calculate the percentage.

Calculating the Cost Price (CP) of the Watch

We know the first selling price (SP1) and the loss percentage at that price:

  • Selling Price (SP1) = \(\text{Rs. } 2,000\)
  • Loss Percentage = \(20\%\)

The formula relating Selling Price, Cost Price, and Loss Percentage is:

\(\text{SP} = \text{CP} \times \left(1 - \frac{\text{Loss } \%}{100}\right)\)

We can rearrange this formula to find the Cost Price:

\(\text{CP} = \frac{\text{SP}}{1 - \frac{\text{Loss } \%}{100}}\)

Now, substitute the given values:

\(\text{CP} = \frac{2000}{1 - \frac{20}{100}}\)

\(\text{CP} = \frac{2000}{1 - 0.20}\)

\(\text{CP} = \frac{2000}{0.80}\)

To calculate this, we can write 0.80 as 80/100 or 4/5:

\(\text{CP} = \frac{2000}{80/100} = 2000 \times \frac{100}{80} = 2000 \times \frac{10}{8} = 2000 \times \frac{5}{4}\)

\(\text{CP} = 500 \times 5\)

\(\text{CP} = 2500\)

So, the original Cost Price (CP) of the watch was Rs. 2,500.

Finding Gain or Loss with New Selling Price (SP2)

Now we are given a new selling price (SP2):

  • New Selling Price (SP2) = \(\text{Rs. } 3,000\)
  • Cost Price (CP) = \(\text{Rs. } 2,500\)

To determine if there is a gain or loss, we compare the New SP with the CP:

\(\text{SP2} = 3000\)

\(\text{CP} = 2500\)

Since \(\text{SP2} > \text{CP}\) (\(3000 > 2500\)), there is a gain.

The amount of gain is calculated as:

\(\text{Gain} = \text{New SP} - \text{CP}\)

\(\text{Gain} = 3000 - 2500\)

\(\text{Gain} = 500\)

The gain amount is Rs. 500.

Calculating the Gain Percentage

The gain percentage is calculated on the Cost Price (CP). The formula for Gain Percentage is:

\(\text{Gain } \% = \frac{\text{Gain}}{\text{CP}} \times 100\)

Substitute the gain amount and the CP:

\(\text{Gain } \% = \frac{500}{2500} \times 100\)

\(\text{Gain } \% = \frac{1}{5} \times 100\)

\(\text{Gain } \% = 20\)

So, the shopkeeper would gain 20% by selling the watch for Rs. 3,000.

Summary of Calculation Steps

Step Description Calculation Result
1 Find CP using SP1 and Loss % \(\text{CP} = \frac{2000}{1 - 0.20}\) Rs. 2500
2 Compare CP with New SP (SP2) New SP (\(3000\)) vs CP (\(2500\)) Gain (since SP2 > CP)
3 Calculate Gain Amount \(\text{Gain} = 3000 - 2500\) Rs. 500
4 Calculate Gain % on CP \(\text{Gain } \% = \frac{500}{2500} \times 100\) 20%

Revision Table: Profit and Loss Formulas

Concept Formula
Profit \(\text{Profit} = \text{SP} - \text{CP}\) (when SP > CP)
Loss \(\text{Loss} = \text{CP} - \text{SP}\) (when CP > SP)
Profit Percentage \(\text{Profit } \% = \frac{\text{Profit}}{\text{CP}} \times 100\)
Loss Percentage \(\text{Loss } \% = \frac{\text{Loss}}{\text{CP}} \times 100\)
SP with Profit \(\text{SP} = \text{CP} \times \left(1 + \frac{\text{Profit } \%}{100}\right)\)
SP with Loss \(\text{SP} = \text{CP} \times \left(1 - \frac{\text{Loss } \%}{100}\right)\)
CP from SP (Profit) \(\text{CP} = \frac{\text{SP}}{1 + \frac{\text{Profit } \%}{100}}\)
CP from SP (Loss) \(\text{CP} = \frac{\text{SP}}{1 - \frac{\text{Loss } \%}{100}}\)

Additional Information: Key Terms in Profit and Loss

  • Cost Price (CP): The price at which an article is purchased. This is the base value for calculating profit or loss percentages.
  • Selling Price (SP): The price at which an article is sold.
  • Profit: Occurs when the Selling Price is greater than the Cost Price (SP > CP).
  • Loss: Occurs when the Cost Price is greater than the Selling Price (CP > SP).
  • Profit Percentage: The profit expressed as a percentage of the Cost Price.
  • Loss Percentage: The loss expressed as a percentage of the Cost Price.

Understanding these basic terms and formulas is crucial for solving profit and loss problems quickly and accurately in exams.

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Similar Questions

  1. A shopkeeper gains 20% in place of 16% loss if the selling price of an article is increased by Rs. 324. The cost price of the article is:

  2. A table was bought for Rs. 3,000 and sold for Rs. 3,200. Find the gain or loss in terms of money.

  3. If the cost of 120 m of cloth is Rs. 9,600, then what will be the cost of 147 m of that cloth? 

  4. The marked price on a book is ₹1,000. In a book fair, it is available for sale with a discount scheme offering two successive discounts of 12% and 8%. What is the final selling price (in ₹) of the book for a customer (rounded off to the nearest integer)?

  5. A shopkeeper sold a pair of headphones for Rs. 5,520 at a gain of 20%. What would have been the gain or loss percent if it had been sold for Rs. 4,370?

  6. The marked price of a frock is Rs. 4,500. It is to be sold at Rs. 2,400 at two successive discounts. If the first discount is 20%, then the second discount will be:

  7. A seller professes to sell his fruits at cost price but still gains \(5\frac{5}{19}\)%. How much does he give for 1 kg?

  8. The price of an article is increased by r%. The new price was decreased by r% later. Now the latest price is Rs. 1. What was the original price of the article?

  9. Ramlal marks up his goods by 40% and gives a discount of 10%. What is his net profit percentage?

  10. Mona purchased two sets of jewellery for Rs. 4,000 each. She sold these sets of jewellery, gaining 8% on one and loosing 6% on the other. Calculate her total loss or gain in this whole transaction.


Important Questions from Profit and Loss

  1. Ram bought a chair at 35% discount on its market price, Had Ram got no discount, he would have had to pay ₹245 more. How much did Ram pay for the chair? 

  2. A shopkeeper bought an item for Rs. 4,500 and sold it at a loss of 5%. From this money, he bought another item and sold it at a profit of 10%. What is his overall profit?

  3. A man sells two articles at Rs. 9,180 each. He gains 8% on one article and loses 15% on the other. His overall profit or loss is:

  4. A shopkeeper selling an article for ₹46 loses 8%. In order to gain 6%, what should be the selling price of the article?

  5. Rahul purchased 80 items from the market. 25% items of the total items were defective and the remaining items were sold at 50% profit. What will be the overall profit percentage?

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